There are many reasons due to which one may want to change their Joomla admin password. It could be because they have forgotten it, or the person who created it is no longer working with them or their account has been hacked. In general cases, you can add, delete, modify privileges in users accounts from the back-end user manager but this requires you to login to your admin account.
If you are aware of the email address that has been used for the admin user and have enabled the "lost password" in the front-end, you can simply ask your host to allow you to change the password.
You Can Change Your Super Admin Password in Two Ways.
1. Configuration.php File:
Connect to your site using the FTP account. Look for the configuration.php file and check the file permissions. Download the configuration file.