Login using the system maintenance user and password created when you installed phpMyAdmin.
It can be found in the debian.cnf file at /etc/mysql then you will have total access.
sudo nano /etc/mysql/debian.cnf
Just look – don’t change anything!
[mysql_upgrade]
host = localhost
user = debian-sys-maint <----use this user
password = s0meRaND0mChar$s <----use this password
socket = /var/run/mysqld/mysqld.sock
Worked for me.