Originally Posted by buffalowings

You can use shear strength, creative ways, or the local bike shop to remove it. Before I bought a chain whip and lockring removal tool to remove the cassette (gears) I scored the plastic disk with a box cutter, and bent it along the score lines, it eventually gave way and I was able to remove it. You can also remove the cassette but that requires a chain whip and lockring removal tool ($12-15 investment from amazon) or the lbs who charges $10 to remove the cassette.