How can I deactivate a User?
STEP 1: First you need to click on SETUP on the right top area.
STEP 2: On the left side, in the Navigation Panel, you will have to click on Administration to access the following item: USERS
STEP 3: After clicking in Users, you will have access to the existing users. Click twice on the User you want to access. Then click Deactivate.
STEP 4: After confirming the operation, the User is deactivated and looses access to backend.