We all have too many passwords to manage and despite our best intentions and practices, sometimes they get lost.
This happened to me recently. When verifying some access before a code upgrade, I found the admin password I expected to work for VPLEX ( cli or Unisphere) did. not. work. I still had the service password, so cli functions were still available, but none the less, the admin credentials are important.
A quick search through support.emc.com turned up https://support.emc.com/kb/15245
Pretty straight forward. Log an SR, EMC will remote in and connect through ESRS (or webex) login with the very secret root password, reset the admin password to the default and flag it to be changed at next logon. You can then change it to your password of choice. using the user reset -u command
Does it work ? You bet..and remember to update your password database.