Having Problems with removing an addEventListener

Greetings Adobe community,

Im currently having a problem with my flash assignment,

I have a:   this.addEventListener(Event.ENTER_FRAME, onPanSpace);

who is causing errors when I go to the next frame:

TypeError: Error #1009: Cannot access a property or method of a null object reference.

          at Confabulation_fla::mc2_3/onPanSpace()[Confabulation_fla.mc2_3::frame1 :13]

I would like to remove this addEventListener when I go to the next frame(which is by clicking on a door) but to be honest, I have no clue how.

So I ask you "How do I remove this addEventListener on my next frame?"

Kind Regards

Notnao