How would one safely eject a Time Machine backup disk?

sorry, I should've been more clear. I know how to eject drives, and I tried to eject it using the method described below, as well as trying through Finder. my issue is that both were unsuccessful, and I was wondering if anyone knew why. after I posted the question I shut down my machine and removed the drive that way, which worked as I expected it to (successfully). afterward, out of sheer curiosity, I re-connected the disk and tried ejecting it using Command > E which was successful, so I'm even more unsure as to what the issue is/was? perhaps just a bug?

oh also, in regards to the shutdown method, I wasn't trying to say I didn't think it was safe. I was just saying it was inconvenient for me (I was working on multiple things at once, and it was just a pain to save/quit all of them) but now I see that it was both unclear and unnecessary. apologies for the obscurity!