If it is grease or gear oil contaminate it is best to replace the shoes/pads however you can boil it out if they are saturated. Extreme caution should be exercised with a fire extinguisher for gas on hand.
Remove the brakes from the car, go to a safe place well away from the car. Dip the shoe in gas, ignite, then wipe away oil/ grease as it bubbles to the surface after flame has subsided. Depending on the level of saturation you may need to repeat a few times.
