You can check this
video that helped me as well to double spend my transaction. It works with blockchain.info only though and if you are using this wallet, you can just wait till the transaction is dropped from blockchain.info only (you should get a message: Transaction rejected by node) and then your bitcoins would be back in your wallet. Just spend them again with a higher fee. It would be marked as double spend then.
If you aren't using blockchain.info, use viabtc.com/tools/txaccelerator/ is the fee of your transatcion is above 10 sats/byte or contact
Quickseller and pay him the miner fee to confirm your transaction.