There is one way you possibly could do it.
First, any provider that has appointments schedule under his/her name would be dangerous to change.
Depending on how badly the user wants to change their name, I "think" it could be done this way.
Whether or not you deactivate or activate a previous user, their user name will be greyed out.
What you "possibly" could do would be to do this with your existing user who wants to change their user name without going to court.
You could log in under their name. In the inbox area at the top, check every section and see if there are any current messages, etc. for that person. Deal with them so that the entire message area is blank. There may be more things that are associated with that user, but I can't think of any. I will leave that up to you.
You could then deactivate that user. Then create a different user with the new user name.
To simplify the idea of this process, you can deactivate any user (except those on the schedule) and open a new user account.
To be completed, if a user is deactivated, this doesn't mean that messages, etc. sent by them to an activated user can't be opened, you just have to be cognizant that there may be 75 messages in his or her inbox that you may not think about.
