In case you are using the Skype App, removing the context menu item is trickier.
One way is to delete DllPath under
HKEY_CLASSES_ROOT\PackagedCom\Package\Microsoft.SkypeApp_15.61.100.0_x86__kzf8qxf38zg5c\Class\{776DBC8D-7347-478C-8D71-791E12EF49D8}
However updates to the app will probably restore this. Adding the following REG_SZ key
"{776DBC8D-7347-478C-8D71-791E12EF49D8}"="Skype"
to
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Shell Extensions\Blocked]
is probably a good idea. Restart Windows to take effect.
