It's a fairly simple procedure. First you need to relieve the fuel pressure in the system by pressing the valve on the test port. Then remove each injector harness connector, disconnect the fuel feed line, then remove the bolts that hold the fuel rail to the intake. After that, you can give the rail a wiggle to get all the injector o-rings loosened up and then pull it up and off. Then you can change which ever injector needs replaced. Reverse the instructions to install everything.
GM Dealer Technician For 18+ Years In the automotive industry for 20+