You can't.
How do i cancel a draw offer?

Once a draw offer has been made, it is completely in the hands of the recipient. The player who offered has no say.

As others have said, you cannot rescind a draw offer after you have offered it. The recipient of the offer can simply decline, or just move a piece. Just hope they do that. haha

The above replies are all correct. It's the same in an over-the-board tournament game. Once a draw offer is made, it cannot be taken back. Your opponent can accept or decline.
In my opinion this is a serious flaw often I just accidentally click it by accident. You should really make a cancel button.
actually I just wanted to tease the opponent by offering a draw and quickly cancel it. turns out indeed you cannot cancel.

In my opinion this is a serious flaw often I just accidentally click it by accident. You should really make a cancel button.
Yes
I need to cancel a draw offer, I made it by mistake in a totally won game, the offer was going to do against the same opponent but in the other game, it would be a shame to tie a game where I have checkmate in two moves :(
Sorry for my english.