Is the problem that the pointy ends are sticking out of the bottom?
If so, then place the strip of wood upsides down, on a couple of offcuts, with the pointy ends facing up.
Use a hammer to gently tap the nails back through the wood, till their heads become accessible, then use a normal claw hammer to pull them up and out.
If the nails are long and bent, and reluctant to be tapped back in without bending, then cut them back to shorter stubs which are more willing to take a bit of a whack.