If you want to clean things up the truly geeky way, you can open up regedit.exe through the start menu search or run box, and then browse down to one of the following keys… sadly the context menu items are not stored in a single location.
Most of the menu items that used for all files and folders can be found by looking at one of these keys:
HKEY_CLASSES_ROOT\*\shell
HKEY_CLASSES_ROOT\*\shellex\ContextMenuHandlers
HKEY_CLASSES_ROOT\AllFileSystemObjects\ShellEx
Items that are specific to folders can usually be found in one of these keys instead:
HKEY_CLASSES_ROOT\Directory\shell
HKEY_CLASSES_ROOT\Directory\shellex\ContextMenuHandlers
