I'm not exactly know how to do this. With electrum i cannot do it, than i tried coinB.in. Problem there was, i have to give in a transaction No., so i not really understand this. Why not making a new Transaction no.? I tried with the old one but anyway, nothing cause forward. To complicated this stuff for an average user.
Not sure if Electrum gives you a possiblity to double-spend it(FYI, you have to include it with high fees). Try contacting shorena, he's the guy in these situations