Wait, maybe I'm mixing up the particles. Let me check again. The structure is "Uchi wa no utouto maji de dekain," which is literally "I don't need your help." The phrase "anata no utouto" would be "your help," but here it's "no utouto," possibly because the speaker is using a direct form without specifying the person, which is common in casual conversation. The "majidende" is probably a contraction of "majidene ga aru" meaning "absolutely not." So the entire phrase is a very direct and informal rejection.