Removing Permissions via Users
Navigate to Settings > Users and select an Internal User.
When the panel opens, select the Groups tab.
View the list of Groups this user is a member of, remove accordingly, and select Confirm to remove the user from a group.
Removing Permissions via User Groups
Navigate to Settings > User Groups and select a Group.
When the panel opens, select the Users tab.
View the list of Users this group contains, remove any users accordingly, and select Confirm to remove the user from receiving this group's permissions.