If you've created an account group in Bill Analyst that you no longer need, you can easily delete it.
Deleting an account group does not impact the list of accounts assigned to you or the assigned accounts in your hierarchies. An account group references copies of your accounts, not your actual accounts. (You cannot inadvertently delete an account using the process, you only delete a copy of the account.)
You can also edit the names of your account groups and move accounts within groups.