It's risky to assume these things though. Going about it the way you suggest it a heck of a lot of faff especially if it gets sold to another buyer or even if there is still time left; if there is a bid it gets noted that you are canceling bids in order to withdraw. Far easier to stick to the proper procedure.
I'm not saying the way you suggest doesn't work for you, but it might be best to explain it's not the proper way and the possible pitfalls when advising others. It is possible someone may believe it is the correct way to go about things and end up with strikes and negs which could ruin their selling account.