One of these should do it:
I. Boot in Safe Boot or boot to a different volume and try deleting from there.
II. In Finder, go to (menu bar) Finder and select Secure Delete.
III.
1. Launch Terminal (Applications/Utilities).
2. Type sudo rm -rf (leave a space after sudo, after rm, and after -rf).
3. Drag the folder into the Terminal window; the path to it will appear.
4. Press Return and type your administrator password.
5. Press Return again.
6. Type exit and press Return for the last time.
7. Quit Terminal. The offending folder will be gone
IV. Many utilities such as Cocktail, OnyX, and TinkerTool System will delete stubborn files.