Removing a guest from a hub doesn't delete the account. In order to actually delete the account from the Hubitat servers you'd need to create an "account removal" case by visiting support.hubitat.com. However, the Hubitat account is not used for presence sensing purposes, and recreating the account will not help resolve the problem you are having with the presence device. The account is only used to log into the app. Once logged in, a virtual device for the phone is created (independent of the Hubitat account) that is later used to communicate with the hub to post geofence events and to receive notifications. If you are having issues with presence, or not receiving notifications, the problem is with the virtual device, not the Hubitat account.
Check out this post for tips on how to solve issues with the presence/notification devices: [SOLVED] Mobile Apps Notifications not available - #18 by bobbyD
