[nightfighter]

The black crap is old adhesive. Circular saw, sawzall, and a couple blades, both wood and metal for sawzall. Cut a small square to get circular saw depth set correctly. Check in basement to be sure that no pipes are up hard against the subfloor. Assuming you have already pulled the baseboard. A good catspaw that is 12" or longer will be very useful. If subfloors run under walls, you have to consider where to terminate your cut as you will want to have good support under the seam. Always best along a joist. Not always possible.

Oh, the black crap will heat up and end up all over your sawblades. It will also have gotten soft enough fom being cut that it will get on your hands when you grab the cut edge to pull up. Cheap gloves are suggested.