While you can't actually delete users from UCM (to preserve historical data)
You can remove them from sight on the User Grid and from any User drop-down in the system.
- In the User Grid, find the user and mark them "Inactive" either by un-checking the "Active" checkbox or by switching the radio button in their User Profile to "Inactive."
- As an added security measure, you can make the "Inactive" user "No Log-in."
- On the top of the User Grid, there is another checkbox that says "Only Show Active Users" you can select this to make the deactivated user hidden, cleaning up your grid. (If you made the user "No Log-in" you can deselect "Show No-Login Users")
Deactivated or No Log-in users don't count towards your User Licenses and shouldn't show up as an option in any of the User Selection areas. They can't log in, or be assigned to contracts or workflows, they can't touch anything or even see anything in your system!
HOWEVER, this user may still appear as an "Owner" or in any of the Supporting Party roles. To make sure they are not recorded as Owner, Primary/Secondary/Tertiary parties, you can follow the instructions Here!