Can't seem to change my user password in phpMyadmin

I have a Joomla site that is turned off because the client hasn't paid their hosting fees. Our former web developer can't remember the password to the user for the admin. I'm trying to reset the password within phpMyadmin in the database under users. I change everything I need, password function to MD5 and then type in my password for the Admin user. After saving the changes I try to log in and it says the username and password don't match.

It's like there is something blocking me changing any fields. I tried changing the email address and it reverted back to the original. I tried creating a new user and it then deleted that user after about 5 minutes.

I did find there was rsfirewall installed so I got into the FTP and renamed that folder so it's not active anymore. At least I hope it isn't.

Does anyone have any advice on this topic? Please help, I've been struggling for two days now and can't find any topics on this. Thanks!