English:

This is graphical guidelines to disable My Site or My Profile link in a portal.

1. Open Central Administration , and click on “Manage service applications”.

2. Open Central Administration , and click on “Manage service applications”.

3. Click on “Manage User Permissions”

4. Remove “Use Personal Features” permission for the Groups/Users.

5. If you can’t see the new rules being reflected in the site. You can restart “User Profile Service”

6. And now, the users will not be able to see My Site / My Profiles link.

English

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.

Updated:

For SharePoint 2010, check here : http://blog.libinuko.com/2010/10/10/sharepoint-2010-howto-disable-my-site-and-my-profile-link