There is no Source Control in File menu

I have added one of my solutions to source control. Now I want to remove it from source control. I searched and found this question:  http://social.msdn.microsoft.com/Forums/en-US/tfsgeneral/thread/79040f47-b634-447c-bc13-1161e572ca9e/

My problem is that in my visual studio, there is no Solution Control inFile Menu. Any ideas why?