Sometimes we used some namespaces and we delete the references. still the using statement will be there. to make it clean we can use a shortcut, which wecan configure as follows.
go to Tools -> Options from visual studio.
Select Keyboard from left items.
then select "Edit.RemoveAndSort"
Now ether the key strokes you like in press Shortcut key text box (suppose ctrl+shift+w).Keep in mind all the three you have to press @ one short.