What size Allen Socket do I need to remove the calibers 7mm or 9mm?

 

9 mm for the front caliper slide pins and 7 mm for the rear caliper slide pins.
The same on all North American XFs with either 380 mm or 355 mm front brakes and either 376 mm or 326 mm rear brakes.
The only exception are some base model Euro/ROW XFs with 326 mm front brakes which take the 7 mm.
Be warned, 9 mm hex drivers are rare and few kits or workshops carry them, but easy to buy one from Fleabay or Amazon.
If you are instead talking about removing the caliper brackets then from memory it's 15 mm bolts all round.