You've been notified about your signature already, I should have given you an infraction right now. You have three choices:
1) Resize the image so it fits the rules
2) Put it inside a spoiler like the other images in your signature.
3) Remove the image

Pick one and apply it in 24 hours!

You should also know that user's insult to moderator and moderator's insult to user are quite heavy rule violations that result in instant ban, provided the offended user requests such action to be taken.