no easy answer. The grout will take some WORK. Multiple stripper applications, scrubbing by hand, maybe even a carbide brush on a 175 if it won't damage the pavers. We have used a carbide brush on tile and grout in order to remove multiple coats of wax.
Maybe some guys will give you some suggestions on a "dynomite" stripper for the grout. It will help to know the type/brand of sealer on the pavers.