shortcut to close a window? (Q Mac)

Good morning, Is there a shortcut to close a window while working in mac? For example, if I am in a transaction report and I double click on a transaction to pull it up and edit it, a window with that account and transaction pops up. I edit the transaction and then move the mouse to the upper left hand corner of the box to close it. Is there a shortcut to close it?
thank you,
Pamela