When you set up a site you have the ability to assign and control what other users can do in the site depending what you want each user to be able to do.
Change User Roles
As an administrator or teacher user, you can change other users’ roles using Users > All Users in your dashboard.
Select the user whose user role you want to change, select their new role from under the ‘Change role to’ drop down menu and then click Change.
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 reasons 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 mouse 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.