I'm having a devil of a time finding the "remove domain" option! :disappointed:
I had the same problem so I emailed. Got this answer from Corona Martinez at TZ:
"Thank you for your email. At this time, the delete domain function is not currently available. We have reported this issue to our programming team and they are working to resolve this bug. This function, as you stated earlier, is not working correctly in Manager 4.1 and Manager 5.0. As soon as this is resolved, I will let you know."