In fact I tried to wait it to become removed, but the tx is being re-broadcasted by other nodes to blockchain.info so I can't spend it 
Read and try to do this:
10 days and still unconfirmed? Since the transaction is irreversible and your transaction might be dropped if it can't be confirmed after a long period.Now you'd better write down the raw transaction of that transaction and re-broadcast it after it have been dropped on blockchain.info.
Re-broadcast: https://blockchain.info/pushtx
Anyway, provide your txid here, it helps a lot.
Re-broadcast: https://blockchain.info/pushtx
Anyway, provide your txid here, it helps a lot.
If you are doing this, use http://www.bitundo.com/. It will give you a GUI which will help you doing the process easily and after signing, you can push it within your wallet because most services reject double spend transaction or post here, someone will help you.