I co-signed for my sister and now my credit score is down because she is always late with her payments, how can I get out of being her co-signer

If she is messing uo your score and likely her score lower by being financial unresponsible there is not chance the lender will let you out of the deal. Her score was so bad before that they needed your better score to qualify. From what you say she is worse off now so they will hang onto to you like white on rice. You need to corner her about this and get directly involved in watching and insuring she makes her monthly payment on time. If she is late the lender also feels you are late so its fanny kicking time. Sorry for the French

Sorry, this is something you needed to consider before you signed for her, in fact if she would stop making any payments they will expect you to make them and could even sue you for the money. So are you ready to start making their payments for them.

There was a reason they needed a co signer, ( they had bad credit for not paying other bills) so why did you think this would be any different.

You could pay the loan off, keep future late payments from being reported OR take over the payments yourself. You pay the creditor, she pays you.

This is another case of trying to help someone and getting bitten in the behind.

Thanks guys for your help and you are all right.