Anyway, that folder is used as a cache for installation files and patches and removing those will cause you to not being able to repair or uninstall applications, and in some cases not removing patches or applying new patches to software.
To remove the contents of this folder correctly, download Windows Installer Cleanup Utility and once installed, run the following command with it:
msizap.exe G!
Reference: http://www.theexperienceblog.com/2009/05/16/how-to-clean-out-windowsinstaller-folder-correctly/
