JMP Delete My Account
JMP Delete My Account is an extension of Joomla! that gives your site members an option through which they can delete their account.
There will be an option for you to set up so that users can only temporarily lock their accounts without having to permanently delete them.
In addition, there is an email address validation feature when users want to delete their account. A code will be sent to their email and they must enter it correctly, which reduces the risk of someone trying to delete their account.
When an account is deleted/temporarily locked, an email will also be sent to that user and the administrator. Note, this account deletion feature is not available with admin accounts.