Do you mean the long panel on the tailgate?
If that is what you are talking about, it is brushed stainless so you should be able to strip the paint without harming the finish, just test in an area that will not be seen by others. You will need to clean it and repolish it when you are done.
Now for the bad news. You need to sand chrome to give it a rough surface so the paint will stick to it. Assuming the last owner did it right, the chrome will never shine the way it should.
You will be better off replacing the chrome around the headlights if you want the chrome to look right.
Did he paint it black or a different color? If it is a different color you might want to repaint it black as that was a standard color for the trim.