You haven't mentioned what OS you are using so it's hard to say. They're all different.
In Windows, you should be able to do it in Add/Remove Programs.
Apparently Adobe 9.0 was downloaded when asked. Assumed it was "updating" 7.0. Now that both an in my computer (Windows7/ Compaq Presario CQ5300F PC). PDF files will not open. ADOBE.com advised must delelte 7.0 . However they said it could NOT be removed as is done with other programs. Said to go on forum and get instsructions. Help.
You may want to try the following:
Run this fix from Microsoft: http://support.microsoft.com/mats/Program_Install_and_Uninstall
Uninstall Reader using Add/Remove Programs
If you want to reinstall Reader, download it from http://get.adobe.com/reader/direct/