There were two bolts holding each rotor on. Those kept them from falling off on the assembly line and aren't really needed now. Where they were are two threaded holes. There's little chance you will get the rotors off without running a pair of metric bolts in those threaded holes to pull them off. If those holes are rusty, just run the bolts in until there's some pretty good pressure pushing the rotor off the hub, then help it by tapping on it with a hammer.

Be sure there's no rust and scale that falls down between the hub and rotor, then coat the mating surfaces with high-temperature brake grease to make removal next time easier.