In Visual Studio, the forms are stuck to the top left corner of the IDE working area like they are pinned there. How do you unpin them?
They're not "pinned", they're actually being drawn there in that position by the designer.
This is a simulated drawing only. The form does not actually function in the designer the same way that it does at run-time. You cannot move forms around or interact with their non-client area in any way (e.g., you also can't click the minimize or close boxes).
This is simply not supported. And I can't imagine a good reason why it should be.