Remove the items stored under your sink to have plenty of room to work.
Start working by turning off the electricity to the disposal by unplugging the cord from the unit to the outlet.
Use a screwdriver or socket set to remove the screws that are holding the discharge tube (drain) from the garbage disposer unit. There should be two screws.
Once the discharge tube is detached, turn it away from the garbage disposal unit so you have more room to work as well as you don't disturb the plumbing. (See picture)
If you have dishwasher, remove the second tubing from the garbage disposal by untightening the bracket that's holding the tube found on the upper part of the unit. (See picture)
Disconnect the lower mounting ring from the sink mounting assembly with one hand in a counterclockwise direction while using your other hand to hold the disposer to keep it from falling down.
Now you have the mounting assembly to take apart. Start loosening the three screws to take out the snap ring.
Use a screwdriver to remove the snap ring. (See picture).
Once you removed the snap ring, the mounting ring, back-up ring, and the fiber gasket will come off from the mounting assembly.
Finally, remove the sink flange by pushing it up through the sink hole.