Depending on your situation, you can either change the users passwords from the admin panel, or create a new password for the main administrator.
You can change or regenerate a new password for each user from the admin panel.
Just open the "Users" table in the Admin panel menu, & click the "Edit" button to edit the user.
ADMIN_LOCKEDconstant, and replace the value ("true") with "false" (without the quotes)
To change the password strength of users who have access to the PHPCG admin panel you must beforehand: