The other methods are not recommended, this is how you can get CCleaner past the UAC (User Account Control) of Windows.
1. Find the install folder (CCleaner), usually its in C:\Programs (if not try C:\Programs (x86).
2. Right click CCleaner.exe,
3. Click "Compatibility" tab
4. Click "Change Settings for All Users" button (at the bottom)
5. Check "Run this program as an administrator".
6. Click "apply" button and click "ok" to close.
7. Restart computer and the problem is gone.
I sent this info to Piriform and told them that this will be a hassle to those who cannot or won't do