Unlocker helps delete locked files with error messages including "cannot delete file," and "access is denied." Video tutorial available. MajorGeeks recommends Unlocker Portable which does not include the Ad-Supported Delta Toolbar.
Some errors you might get that Unlocker can help with include:
Cannot delete file: Access is denied.
There has been a sharing violation.
The source or destination file may be in use.
The file is in use by another program or user.
Make sure the disk is not full or write-protected and that the file is not currently in use.
Offers to install the Delta toolbar during installation. Uncheck that by selecting Advanced install. See the video above at 30 seconds for more. Unlocker Portable does not include the Ad-Supported Delta Toolbar.