When you create a site you have the ability to assign and control what other users can do on the site depending on the you want each user to be able to do.

CHANGE USER ROLES

As an administrator or teacher, you can change other users’ roles using Users > All Users in your dashboard.

Select the user you want to change, select their new role from under the ‘Change role to’ drop down menu and then click Change.


REMOVE USER

Remove user is used when you want to remove a person as a user from your site.

Removing a user doesn’t delete their username.
It is better to change the display name if your reason for removing a username is to change the name displayed on posts or comment.

The alternative option is to change their role to subscriber — subscribers can only edit their profile.

 Go to Users > All Users 

Hover your cursor over their username and click Remove

To remove multiple users, select each username you’d like to remove using the check boxes, select Remove from the Bulk Actions drop down and click Apply.