PB Blaster is your friend, i'm sure its just rusted on there pretty good. Spray some PB blaster around the hub where the rotor meets the hub and on the backside too, should penetrate and you can knock it loose.

If you took the caliper off and the retaining screw, that's all you need. Leave the car in neutral so the wheel can rotate as well (not sure if you can do this with an auto, I do it on my stick though), that way you can hammer the rotor all around evenly as you go.

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2018 Ram 2500 6.7L Cummins 68RFE
19k miles -Bright White/Black - Big Horn Sport - Crew Cab Short Bed
2013 X5 35D (CEO's) - Born on 5/17/2013 -
82k miles - Alpine White/Cinnamon Brown/Premium Pkg, Sport Activity/Premium Pkg and Sound/20" Style 214/Running Boards