If necessary, you can block a user’s access to the service portal.
To do this, go to System apps > External users. Open the profile of the user you need to lock. On the right side panel in the Account status section, click the 
icon.
After that, the account status on the user page will change to Locked. The user will not be able to log in to the service portal. Their license will be unoccupied.
Note that only users with the Active status can be locked.
The status of the user account remains Not registered until the user logs in to the portal for the first time.
Unlock an external user
If you want to restore user’s access to the portal, go to System apps > External users. Use search to find the user you need and open his or her profile. On the right side panel in the Account status section, click the 
icon.
The unlocked user will be able to log in to the service portal again.