To remove a team member from access to a case, perform these steps.
Click "Cases" in the top blue menu bar
Click the target case
Click the "Participants" tab in the case slide out panel
Hover your mouse over the target user
Click the X icon near the target user
Note that you can not remove the team members that have the Team Managers, Team Editors, or Team Viewers permissions. Team members with those permissions are managed at team level