You can either "delete" or "deactivate" users, and both deleted and deactivated users do not count against your subscription. You can "deactivate" them which hides them by default or "delete" them by first searching for the user and clicking on their username them:
- Scroll to the bottom of the page and click "Delete User" and follow the instructions/confirmation
- Click on the "Membership" tab
- In the "Renew/Change, change their "membership" to "Deactivated"
Deleted users will have their personal information removed from the system, but will maintain your stats/reports and will display as "deleted" in cases where the user would be displayed. You can not recover or undelete a user.
Deactivated users will no longer come up in searches unless you specifically do an Advanced Search and check off "Include Deactivated" when searching. They are hidden, but can be re-activated.