In order to cancel a user from a security role you need, when logged in as an administrator, to click the User Accounts button in the menu.
Click   beside the user you want to cancel the Security Role.
Click Manage Roles for this User at the bottom.
By checking “Send Notification” a notification email about the role cancellation will be sent to the user.
 

In order to cancel the roles click the red X beside each role.
Click Cancel to return to the User Accounts page.