Why can't I uninstall programs using CCleaner?

Question

When I try to uninstall a program using CCleaner I get this message "You do not have privileges to perform this operation". I am the only user on this computer.

Answer 1

With ccleaner in particular or in general? 
Very basically and generally you can, at the minimum, trash the application, prefPane, or whatever it is you want to uninstall.  But you should be aware of some other details:
1. Apps may install login items or other startup items.  Hopefully the ones the install other startup items will also supply their own uninstallers.  Use the third party uninstaller whenever possible if it is supplied.
2.  Preferences are usually stored in ~/Library/Preferences generally as .plist files.  You could, if you can't identify the plist file just leave it alone.  If there is no program to use it the plist is just taking up space.
3. Many apps also can create stuff in ~/Library/Application Support.  Like the preferences these to could be ignored.
4. Like 2 and 3, some apps might use ~/Documents, ~/Movies, etc.
5. Apps installed with .pkg or .mpkg installers usually will install their apps into /Applications.  But except for stupid authors who for some odd reason want to supply their apps with .pkg installers where it only installs a single application, .[m]pkg's will usually "spray" other stuff into your system into any of the places I mentioned previously but also may install into system level places if they request the admin password.  Hopefully these installers will also supply some kind of uninstaller, either installed as part of the installation or supplied separately.
Some additional references:
The X lab: Uninstalling applications
Uninstall Mac Applications