If we don’t remember the login password of SSO ( admin@system-domain ) , we can reset the same using the rsautil sso command but we require the Master password of the SSO which was provided during the installation and without the Master Password , only way is to re-install the VC but its really very pain to do the same , from the below blog they have  suggested to try two method , one by identifying the SSO DB user name so in most cases we use to give the same password for admin and DB , next  is unsupported method by VMware is to build a temp SSO db and copy the hash to your prod db .

Method 1.

Login to the VC and find the below path and open the config file to find the DB password. In most cases we used to have the same password for admin and DB , in my case also the same so I am able to reset the password..

Method 2 :

http://translate.google.ie/translate?sl=de&tl=en&js=n&prev=_t&hl=en&ie=UTF-8&layout=2&eotf=1&u=http%3A%2F%2Fwww.die-schubis.de%2Fdoku.php%3Fid%3Dvmware%3Avsphere%26%26_sm_au_%3DiVVqjkrsQ0sLqFW6&act=url

I tried it my lab and the result is success , able to change the password ..

Reference :  http://translate.google.ie/translate?sl=de&tl=en&js=n&prev=_t&hl=en&ie=UTF-8&layout=2&eotf=1&u=http%3A%2F%2Fwww.die-schubis.de%2Fdoku.php%3Fid%3Dvmware%3Avsphere%26%26_sm_au_%3DiVVqjkrsQ0sLqFW6&act=url

http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=2034608

https://communities.vmware.com/thread/428929