Go to Administer > User management > Users in the administrator toolbar.
A survey of all registered users is displayed, including some additional information such as the status of the user account (active or blocked), the role of the user, how long the user account has existed and when the user last logged into the website.
If necessary, use the filter on top of the page to reduce the number of results on the page.
Click on Edit in the Operations column to change the account details of a user.
Use Update options to (un)block one or more users, to grant new permissions to users or to remove some of the users’ permissions.
Keep into account that when a user account is deleted, all content that was created by that user will also be removed from the website. It is advised to block a user account, rather than to remove it.