Probably nothing. Not all full length guide rods have the hole. Press in on the guide rod plug, rotate the barrel bushing to release it, then remove everything as normal. Just remember it will be under tension so point everything in a safe direction.
"The 1911 was the design, given by God to us through John M. Browning, that represents the epitome of what a killing tool needs to be. It was true in 1911 and it's true now." - Col. Robert Coates commanding, U.S. Marine Corp Special Operations Command Detachment 1 (DET 1)