Deactivate/Activate user
In the back-end menu, go to Admin › Management.
To Deactivate/Suspend the user click on the blue circle that’s located all the way to the right of the user
A small window will pop up for Confirmation
If you want to Reactivate the user again, click on the gray circle that’s located all the way to the right of the user
And a small window will pop up for Confirmation