It is against forum rules to all-cap a thread title. Please do not do that again...

It is not possible to take back a bid. In ways, you can jack up the bid price without needing to worry about losing gold on the bid in question. I know you are probably genuine in making a mistake, but to counter players like what I listed above, that option has to be disabled.

I would agree though to an idea of a window, time frame, in which you can retract a bid, like 10 to 20 seconds.