I think it'd be nice to be able to cancel all trades/multiple trades at once. I recently had to cancel all the trades I had up and it would be a lot easier to be able to cancel them all in one go. Maybe add a checkbox next to the trades with a button that says "cancel selected trades", and another that gives you the option to cancel all of them. There would be an "are you sure?" message to prevent accidental cancels.

Also, in the same vein, I think it should take us back to the manage trades screen when you cancel one. It honestly doesn't make sense to me to not take you back and instead giving you a "this trade doesn't exist" (like yes I know, I just canceled it lmao). And even if the checkbox to cancel multiple trades doesn't
happen, taking us back to manage trades would be a lot more convenient and make it easier to cancel trades.