I'm putting 3/4" prefinished wood on plywood. I've pulled up the old linoleum. It was stapled and glued around the perimeter only. Do I need to get that glue up before putting the down the underlayment?

I'm thinking I only have to be concerned with the big chunks that might create unflat areas. Is that right?

If I do need to remove it, what product or technique works best?

Thanks! So glad I found this site!!!

Use a putty knife, or a belt sander with 36 grit.

If you are nailing the new floor in place, I wouldnt worry about the residual glue IF it is merely a thin skin of it. If ridges are there, then you will have to remove those.
However, if the new floor is being glued in place, all traces of the glue must be removed to avoid incompatibility issues.