The rear grab handles have three "pins" that when pushed in, expand locking tabs on the back of the handle assembly. Two of them are above the handle (the handle actually rests against them in the up position) and the other is the outer portion of the garment hanger. Gently pry all three pins out. They can come all of the way out but really they only need to come out 1/2" or so. You should feel a positive stop when they are out far enough. Then gently pull outward as you wiggle the assembly up and down. As a last resort, use a broad faced tool to pry it away from the headliner. Use extreme caution to prevent damage to headliner and handle assembly.
I didn't take any pics when I renewed my headliner so I drew you a cross section sketch. It'* nothing fancy cause I'm not an artist. Maybe harofreak took some picks of his while they were out?