It should be under add/remove programs - mine is in XP.....however you may be able to remove it by downloading and installing it again, then un-installing.
However you may find that you get errors trying to re-install if there are previous installer files on there - in which case you may need to run the Windows Installer CleanUp Utility first.
For a much lighter version of a PDF reader try Foxit
Unlocker is used to help delete files which cannot be deleted because they are currently in use/being accessed by a program - I don't think that applies in this case from what I can see.
However Unlocker is indeed a good free program to use in the right circumstances - and one I use