Tile to Hardwood

I am in the process of removating a kitchen. I will be removing the ceramic tile and installing a nailed down hardwood floor. After I get the tile up how do I remove the thin set that remains on the sub floor? Currently there is 1/2" plywood over 5/8" plywood. I had installed the tile floor 20 years ago. I had to replace the 1/2" in some areas where I removed an existing tile area and I know that I glued and screwed the 1/2" in those areas, so removal of the 1/2" may be next to impossible.
Any suggestions on how to remove the thinset w/o having to remove the subfloor?