At the moment user’s do not have the option to delete a transaction. It’s a feature we’re working hard to implement.
However, if you have created a transaction that is now void as nobody joined it there is no need to delete this transaction. As long as you didn’t share the join code with another party and as long as nobody else joins it there is no reason to delete the transaction.
If a transaction is created and not joined or joined and no payment is made it is marked as redundant on our end.