It may happen that even emptying the Recycle Bin Finder certain documents or folders are not deleted. The problem depends on the permissions of the files. In any case you can force emptying the trash via the Terminal (Applications / Utilities) or using some free utilities.
Launched the Terminal, type sudo rm-R to a space, then drag the files in the application window and press Enter. If prompted, enter the administrator password and then type y to overwrite privileges.
As an alternative to laborious way you can use Terminal BatchMode ￼ that besides allowing you to manipulate the permissions of files and folders, it also includes a command to force empty the Trash: