Most rotor manufacturers paint the bells these days, meaning they stay looking rust free for years.
At to the question.
Yes there is.
The vehicle needs to be on level ground, you'll need to chock the front wheels, and put it in 1st or reverse for a manual, or PARK for an auto.
Crack off the wheel nuts ½ a turn on the wheels you want to remove.
Then lift the corner you'll be painting, and remove the wheel.
You can turn the hub by releasing the parking brake, as the vehicle shouldn't move if it's in gear with the wheels chocked.
Only paint the visible part of the rotor bell, as the wheels need to go against steel, not paint.
Otherwise it's a pretty simple operation.