A few options, courtesy of Isaac Newton and his third law of motion:

1. Jettison the propulsion system in the direction of travel with really high speed (how high depends on the relative masses of the ship and the propulsion system; this might not be possible at all).
2. Have everyone get onboard a shuttle and launch it really fast going in the opposite direction of travel (and have it moonwalk into orbit, you smooth criminal).

A few options, courtesy of Isaac Newton and his third law of motion:

1. Jettison the propulsion system in the direction of travel with really high speed (how high depends on the relative masses of the ship and the propulsion system; this might not be possible at all).
2. Have everyone get onboard a shuttle and launch it really fast going in the opposite direction of travel (and have it moonwalk into orbit, you smooth criminal).

Though come to think of it, deceleration from relativistic speeds to orbital speeds over the distance of the length of a spaceship would be more than fatal for the crew and likely the ship/escape pod.