needs a trash can

You can just select Undo, or press Command-Z. The Undo in Quicken Mac is pretty comprehensive (e.g. almost everything is un-doable), and you can keep Undoing repeatedly to step back through things you've done. Of course, if you figure out you mistakenly deleted a transaction a few days ago you can't retrieve it, but for a simple "whoops, I didn't mean to do that", it's easy enough to do Undo.