Quote: "I know I may be late..but i wanted to say the easiest way to delete entitys, is by LEFT clicking it first, then RIGHT clicking it and it should be deleted. So basically your left clicking it like your going to move it...but then you just right click to delete! simple"
True, but in the case of removing a segment door and leaving just the frame, Thraxas is correct and your method will not remove the door and leave the frame. You have to place the door, switch to "entity mode", move the mouse over the door, right click, and when the properties for the "door" come up you press DELETE to remove the door and keep the frame.
There's no problem that can't be solved without applying a little scripting.