User Role Blocker

A simple and nice plugin to block existing users from logging into the admin panel by assigning them to the ‘Blocked’ user role, as simple as that. If the installation is okay, go to any user’s profile and you can find a new role called Blocked in the user role dropdown. Just assign any user to that role, and the user will be taken to the ‘blocked’ URL whenever they want to log in.

Unblocking a user is easy. Assign them to their previous role and you’re done!