Romans 6:7 : For he that hath died is justified from sin. Or, according to the marginal reading in the American Standard Version, "For he that hath died is released from sin." Meyer translates it, "Whosoever is dead, is acquitted from sin." If a slave died, he is free from service to his master. If a slave of sin dies to sin, he is free from service to his master. Sin rules him no more.
Thus, in Romans 6:2-7, Paul answers the question of the first verse--namely, "Shall we continue in sin, that grace may abound?"