In hitbtc, you can. Once you ordered to send the money and confirmed it you can always cancel it but the fee will be reduced. So if your money is. 05 btc and the fee is .0015 btc then when you cancel it, the funds you can get is only. 0485 btc.
It can be done by the exchanges only as they will do by their own pocket but in blockchain bitcoin transaction cannot be cancelled once it is confirmed by the blockchain. Until the transaction is not confirmed or included in the block it will get cancelled for example if you have set very low fee then your transaction will get cancelled automatically after some time as no miner will included it in their block.
Well said but i would like to clarify that theres no cancelation of your transaction if you do set out very low fee.Its still broadcasted on the network but
due to low fee it would have the tendency or chances that it will got stuck or wont confirm at all yet it wont be pushed by miners but on the current condition
theres no problem with fee though yet they are on the lowest possible amount.
Ya you are right that right now the fees is low but in past when the fees was high that time if you have set very low fee then it can cancelled automatically after some time/days. As it is not broadcasted by any miner. I have experienced this as once in that time i had set low fee and was waited for more then a week for my transaction to get cancelled and then i got my coins back in my wallet.