In these lines, Romeo is convincing his servant to help him with his plan and get out of the way.
Romeo is about to go visit Juliet's tomb, and he is planning on killing himself there. He tells his servant that he will go retrieve Juliet's ring, and that his wish must be respected. He also asks his servant to leave, and tells him that if he were to come back, he would kill him. He tells him that his plan is a wild one and that his resolution is fiercer than a tiger or the raging seas.