This is graphical guidelines to disable MySite or My Links link in a portal.
A. Open Central Admin , and click on SSP which serve My Site.
B. In the SSP Management page, click on “Personalization services permissions”
C. Select the users/group, and click “Modify Permission of Selected Users”
D. To remove “My Site” links, uncheck “Create personal site” , and to remove “My Links” link, uncheck “Use personal features” , and click OK.
E. After you’ve saved the modification, the user will no longer see the links.
For SharePoint 2010, check here : http://blog.libinuko.com/2010/10/10/sharepoint-2010-howto-disable-my-site-and-my-profile-link