Depending on your access permissions the list of users might not be visible.
The "User Administration" module can be located from the menu under System.
From the list of users using filters
Having the list of users open in the User Administration application you can use filters to find the user you are looking for. Clicking the user in the list will open a drawer with additional information.
From the list of users using filters
Having the list of users open in the User Administration application you can use filters to find inactive users by toggling the Deleted Items switch.