The rear rotors/discs on the Infinity FX35 have an integrated drum that contains brake shoes for the parking brake. Even if you release the parking brake the rotor/drum can and usually will be locked onto the hub. Remember that brakes get extremely hot and all of those hot/cold cycles cause the metal to expand and contract. This causes the rotor/drum to be locked onto the hub. The way to get it off is to spray Liquid Wrench or WD40 into the places where the hub and rotor meet which is around the diameter of the rotor/hub interface and where the lug bolts protrude. You need to spray and let it sit perhaps 15 minutes and then repeat the process. Then you need to take a 5 or 10 lb sledge hammer and hit the rotor around the drum area VERY HARD. You can't tap it or hit it softly. You have to hit the drum almost as hard as you can. All of the components there are extremely durable and rugged so don't be shy. Just don't hit the lug nuts or the rotor surface - that would be bad. Hit in an inward radial motion onto the drum. Then grab a pry bar about 18 inches long and stick it behind the rotor and pry against the caliper bracket pulling outward away from the car. Doing this repeatedly will eventually cause the rotor/drum to come loose. Be patient, keep working the process, and don't give up.
One thing to note. I read on other posts that you need to pull off the rubber grommet and reach in through the peep hole and release the parking brake adjustment spring. This is a red herring. In other words this is not necessary to pull the parking brake off in my experience. It did not cause any tension on the parking break assembly at all. It is important to release the parking brake.
I hope this helps and I hope you are not doing this work on a Sunday night going back and forth to the auto parts store. Be patient. If you are not patient then just ask the Holy Spirit of God to help you because there is no other way to get patience. If you don't know God then you need to go find out who Jesus Christ is and then you will find the only way to God. Then you need to totally submit your will to the will of the Father. Then you stop being so impatient and angry with others as you allow Christ to work in your heart. Then when a simple brake job goes long and the wrong way...you'll be patient. God bless!
If you have rear Disc brakes like mine, you'll just have to smack the crap out of it, once the caliper is off. Take a look at a new rotor, and see where the rotor will separate from the hub; then spray penetrating oil (Liquid Wrench) around the lug bolts and around center hub. Then get a good hammer and a good pry bar. TIPS: Be aware of the lug threads, don't "doink" them with the hammer. Also, take care to not harm the surface of the rotor, unless you're replacing it. That said, pry and smack the rotor after the oil has soaked in, it'll come off.