To assign or change permissions of a user you must change the user role. Navigate to My Groups and click Manage Members.

Select the User Role to be assigned to the user in the dropdown menu. Note that when a new user becomes a member of the lab, the default user role is assigned. This setting can be changed when setting permissions. You can also find the option to change the user role under Group Members in the Configuration menu

When changing the user role to blocked, the user can no longer access any data in the lab anymore. In addition, this user is also not counted as an active seat in your license plan. After blocking a user the license taken by the user will automatically become available for another user.