I just did that. It's ridiculous. The engineer who designed the front end so you have to remove the front bumper cover to remove the headlight ought be be made to come to your house at his own expense & change it for you. (among other things) I found a video on youtube that generally showed how. Sorry I don't have the link. You'll have to search. you basically have to remove the wheel, go in through the wheel opening, remove the inner fender liner, pull out the bumper cover at the side, after removing all the screws you can find & pry it out a ways to access the back of the light & the screws that hold it in. Royal pain in the butt. Have fun!
Kinda funny to hear about having to remove the bumper since the 2009 Malibu I traded in for my 2014 Regal also had the same issue.
Good thing after 5 years I never had to change or have to pay to change my headlights.
It is common practice on new car designs to have to remove the bumper to access the lower attachment bolts for the headlights.
If you are trying to replace a cracked headlight let me know I need a round dust shield (the thing that protects the d1s h.i.d. bulb). I just purchased a gs that's missing one, it can't be a coincidence that the bulb is burned out it's obviously a crucial part to keep out water.
Today I removed my bumper/grill and replaced both ballast with new bulbs in less than an hour. A total of 12 T20 Torx screws to remove bumper/grill and 4 screws for each headlamp assembly. I removed both front wheels just for more space to get to the 3 T20s that hold the bumper/grill to the wells. It's not necessary though. The link below was all I needed to pull bumper/grill and holding help to put back in place. Saved me hundreds$$$$$$$$$$$$$$