This relay worked fine for a couple of years on a bath fan switch. I have exchanged emails with Zooz, but no luck. They pointed me to a home assistant article . I have quickly tapped zwave button on relay 3 times, , flipped the switch up/down 3 times. While in exclusion mode. It still shows up in zwave settings. and has events in device mode.
Any other ideas before I replace it. Not sure how I will remove it from hubitat though.
What do you mean with "in device mode"? From your screenshot, I see actual events (not just commands), which is suggestive of the device not having "dropped off" your Z-Wave network; these would be generated by reports coming in from the device, which would mean that communication is not a problem. Can you back up a bit and explain what led you here? Maybe a problem with the device itself not doing something?
That being said, if you are trying to perform an exclusion and it's not working, that is odd. I'd use the Z-Wave button on the device in the event you have the parameter to enable this using an external switch disabled (an option on this device), but it sounds like you have. The only other thing I might suggest is a factory reset on the device, a "Remove" from Hubitat (should eventually appear in the Actions tab on the Z-Wave Details table) after you've removed it from any apps or swapped it out with a temporary device (or the "new" one if you get it included again), and an attempt at re-inclusion. If you have access to another Z-Wave controller, such as another Hubitat hub or another home automation system/controller, you could also try a general exclusion (or inclusion if you think it's reset or excluded) just to rule out an odd problem with one specific hub.
I see the event is the device tab. I don't see the events until I look at ZEN51 in devices. In Zwave setting there is no log. I have changed no defaults on this device, I have tried both zwave button and toggle switch for exclusion with no luck. I will circle back with Zooz since it is showing communications.
Where else are you looking?
where else should I look
I think that's the best place, particularly for troubleshooting, but it sounds like you were looking somewhere else and noticing what you believed to be a problem. That is why I asked: I'm curious what you are looking for and where (and what the problem is). 
the problem is the relay has stopped responding to zwave commands to turn on and off. Relay works fine with switch. Led me to (falsley) concluding it had fallen off zwave network. I have asked Zooz about this will see what they say.
That is helpful to know!
The first thing I'd check is that you have the "smart bulb mode" parameter disabled (this is also what it's called in the UI with the default driver; may vary if you are using a custom driver, or parameter 6 if you wanted to use something like the Basic Z-Wave Tool to check or set the value). Otherwise, perhaps their support team will have additional ideas.
Zooz support replied at 10PM last night. They suggested the exclusion process again, and I patiently used the zwave button on ZEN51 while hubitat was in exclusion mode. Finally, hubitat announces that it has excluded unknown device. I shut down hub for 5 minutes, Powered back up. It is still showing up on Zwave settings, how long should I wait for it to disappear. Should I hit refresh?
The fact that it said "unknown device" means it doesn't know it was this node/device, and it won't disappear from the table (or your Devices list) on its own, which is what would happen if it did. (It should, but maybe a previous reset or exclusion with another controller was successful, for example.) So, you'll need to use the "Remove" button in the "Actions" column to do so yourself. If you don't see that, a "Refresh" might help, but waiting should make it show up on its own eventually, too.
Okay no remove button yet. I have hit refresh again
Still no remove button. what happens if zwave node loses power for some time. How can I remove this node?
If your device was reset or excluded, Hubitat no longer knows about it, so it's practically lost power for all the hub cares. (The fact that you don't have a "Remove" button yet it suspicious, however -- maybe try a reset on the device, too, just to be sure?)
That being said, the node still being present shouldn't really prevent you from doing anything -- again, assuming you've generally excluded or reset it. (The hub has no other way to know what a Z-Wave node is beyond its hub-assigned node ID, lost when one of these happens.) So I wouldn't let that stop you from whatever your next plan is.
Also, did you include it with Z-Wave Smart Start in the first place? If so, are you sure the node didn't exclude and then automatically re-include because it's still in your Smart Start list? (This is something you'd have to have done in the first place -- and can manage -- with the mobile app; if you added it via traditional inclusion from the web UI, this isn't it.) Just to make sure it's maybe not a new node the re-appeared but looks similar.
No I didn't use smart start. I will try another factory reset. I can physically replace it with another relay include that on go down the road. I just don't want this device mucking up my zwave network.
So I tried factory reset on ZEn51 while Hubitat in zwave exclusion. LED blinked indicating factory reset, Hubitat then showed remove button on zwave settings for ZEN51. Clicked that, then refreshed Zwave settings. That button now gone. Powered down Hubitat for an hour. Powered back up at the same point, refresh or rebuild route on that. Sent all this to Zooz, they now want video of me doing that. Any other ideas on how to exclude this module?
Are you on Z-Wave JS? If not, you could try even just temporarily switching (if supported on your hub) to see if that helps with the removal.
But it's quite likely the device had already been excluded. Is there a reason you haven't just tried to re-include and then revisit this "lost" node if you have problems? It's a good idea to avoid but not a recipe for certain disaster.
not on ZwaveJS. Not sure it is supported on C7.
I will try re-include. Thank you,
Waiting for the "Remove" button to appear (and work) is the only way, but if you can't do that, this is still true:
So, I'd just keep things like they are if it works.
thank you.