There's a nifty little flag and output you can use to open and close the door with one button. If this is a func_door_rotating, you can go into the flags tab and check the "toggle" flag if it isn't already. Then for the related func_button, tell its output to be:

My output named: OnPressed
Targets entities named: <the name you gave your door>
Via this input: toggle
The rest is on your preference, just make sure "Fire once only" is not checked.

That way, if your door spawns closed, a toggle action will make it open, then pressing it again will close it. Since there's only two different states this door can be in, the toggle output is available. This option is also available to the other door entities, like: func_door and prop_door_rotating, and many more.

And the "toggle" feature can be used for the output of other entities as well, namely the "logic" entities!