JA wrote:
We're remodelling a basement and need to remove hard cut (masonry) nails
that are along side a window. There is no way to reach the nails with a
hammer, so pulling them out or pounding them flush is not an option. (They
are in the concrete block wall around a window frame and we need to remove
them to slide sheetrock or paneling into the space.)

Are there saw blades that will cut through them?

Bending them back and forth with a vise grip will break
them off. Grab them as close to the cement as possible.