Must be an odd thing with Safari's date picker, though it's odd it doesn't render that way for me. This post is 7 years old but still accurate with a quick test (including the link to the demo) for me. 
https://stackoverflow.com/questions/52218578/clear-html5-date-input-on-ios
If you can use a different browser, even desktop Safari, for this, that should work.
Okay, I have a weird issue - maybe it’s not so weird.
I have an Aeotec Series 7 Pro contact sensor using external magnet and the device shows closed in HE, but when DSA runs (or I test it) it shows this sensor as open.
I had this working previously, but had to change the magnets and I think the issue is the new magnets are “normally open” vs previous magnets that I could wire either way. In HE I did have to change the preference to “report closed when magnet is open” and it appears to work as expected (gate opens, device reports open and vice versa).
So now I’m curious as to how DSA is “saying” the gate is open when the device is reporting as closed. Can’t get any screenshots tonight and I have not tested DSA with gate physically open (yet - will do tomorrow). Just wanted to get the wheels turning.
Interesting that on the latest beta, the RESET button in the Safari picker now CLEARS the date/time and lets you save it a “empty’.
This appears resolved. Not sure why. I completely removed DSA, reinstalled, issue remained. I flipped the normally open/closed setting in the device preferences last night - issue remained.
Just now i was going to see if opening the gate would clear it, but before i did i ran the test and it did not report open. opened the gate and it reported open. closed it and it again reported correctly.
something weird in the ether i guess.
