ote:
I guess that depends on what kind of plug it is. If it's a screw type plumbing plug with a square head on it, then is should unscrew. But, I didn't think those wall boxes had a threaded opening, just regular pipe.
A pic would help.
Usually the dryer can't and doesn't need to go back all the way anyway. On mine the vent exists and makes a
90 turn, hence the dryer is probably 6" or so from the wall. So, I don't see any problem with where yours is located. And what's the alternative? Tear open the wall and re-route it?