Step 4: Discharge the capacitor
Locate the capacitor, it should be near the big fat chunk of metal, the high voltage transformer. Then get your alligator clips and very carefully touch both terminals of the capacitor...
You may get an loud "SNAP" (which is unlikely) and that indicate the capacitor is discharged, do this a few more time to really make sure the capacitor is discharged..
And you're done! The microwave is safe to gut out!