Here I went ahead and did it real quick for you since it was bugging me too:
Unscrew the strain relief and remove the outer shell locking screw from the side of the plug.
Gentle push the locking slide in and pull towards you and the slide and small spring that is behind it will pop out.
Us a small screwdriver or your fingernail to pry/remove the locking bar from the barrel of the connector. You can take the little piece of foam padding out as well.
With it all removed it should look like this. You can put the red locking slide and the small spring back in for looks if you like. I did. But it is not needed.
Once its reassembled you have a normal non-locking, high quality, black, female 1/4" plug