Sometimes cPanel does not remove the database correctly and leaves behind files.
Take a backup and then remove the files in
/var/cpanel/datastore/<username>/
Then
ERROR: PleskFatalExceptionUnable to connect to database: saved admin password is incorrect.
0: /usr/local/psa/admin/plib/common_func.php3:190psaerror(string ‘Unable to connect to database: saved admin password