I'd go further than that. I would suggest re-setting the password to something you know using one of the well known tools that are out there. Once you have this I would looking at browsing history to establish if your son used any social media sites or e-mail solutions. You will likely want to try and have these removed too or in the case of something like Facebook maybe have the page turned into a memorial for his friends to pay respects to your son and remember the good times he had before his untimely departure. Other sites have teams that help in these sort of sad situations.
It must be a hard time. Don't rush to delete anything, establish what he had and then act on one thing at a time.
Read the instructions on the site. Using the utility to change the users password doesn't always work right. Usually what I'd do is set the admin accounts password to nothing so there isn't one. You have to enable the account for Vista and Win 7. If it's a Mac though then your SOL