See this excerpt from an earlier post on the subject:
Additionally, there are registry keys and entries that Registry Cleaner cannot delete because the programs that install them set their permissions to prevent deletion. PowerTools will usually indicate those entries when you try to delete them after a scan. On my system, Adobe Acrobat is the biggest such offender. If I really want to get rid of such entries, I manually reset their permissions to allow me to delete them myself - I use Registry Workshop, but you can also use Regedit. Do this carefully - you can disable programs or your system if you're not careful. If you decide to go this route, research registry entry permissions (or something similar) on Google and get a little smarter on the process.
In short, you can use RegEdit or a similar registry editor to manually reset the permissions of those registry entries to allow them to be deleted. Typically, you right click on the entry in question, select Permissions (or something similar), and select Modify or Full Control or Edit (or, again, something similar). You'll then be able to 1) delete them yourself in the registry editor, or 2) return to PT and have Registry Cleaner delete them. Be sure to do some research on the subject first as stated above to avoid potential headaches.
Good luck!
