Rent a trash container to dispose of the Sheetrock as you complete the demolition.
Remove both the ceiling trim and the baseboards, along with any chair railing, using a pry bar. You can save the molding for reuse or dispose of it in the trash container.
Put on work gloves, a pair of safety glasses and pick up a 3-pound hand-sledge.
Approach the Sheetrock and knock a hole into it with the hand-sledge at the top corner. Reach inside the hole and pull the wallboard away from the studs. The wallboard will likely break off into a big section.
Continue to break out holes and pull the wallboard off the wall frame until all of it has been torn down.
Inspect the studs for nails or screws. Pull out the remaining nails stuck in the studs with a nail puller, or unfasten any protruding screws with a screw gun to finish the job.