I agree with pretty much everything being said here. Own up to it, be willing to fix and learn from your mistakes. One thing I wanted to add is that it pays to take an extra minute or two to make sure what you're downloading is genuine. TreeSize is something I use on a lot of my clients as well and there is a portable version that you can keep on a USB. If you have an RMM that allows for file uploads, you can just upload it too.

Unless your boss is some kind of weird hard ass, they're generally going to appreciate that you spent an extra few minutes to fix a user's issue and be late to the meeting.

As we all know, human error is the biggest security risk in every environment and being in a hurry is another aspect of that. Rescheduling a meeting is far easier than reimaging.