Hi Jose, I had to remove flooring in my hallways both upstairs and down to allow house movers to cut it in half. I removed the upstairs with prybars. I ended up tearing off the lower lip from the groove side almost every time. By the time I started on the downstairs someone had recommended a sawsall with a long bi-metal blade and it worked great. You just slide the blade under the board and cut the nail. Once you get going you can develop some speed. Some floor guys said I didn't need to remove the residual nails but my wife and I sat in front of the TV and pulled them out with bullnose nippers.