I would grab a skilsaw with a blade I didn't care about, any old
carbide general framing will do, and cut through shingles, plywood, and
all between each rafter (a wormdrive saw helps). Remove each rafter
like that with plywood and shingles attached. If you want the job to
take 3 or 4 times longer, make a bigger mess, and be more aggravating,
then strip the shingles seperately.