Office For Mac Excel - False File Reservations

I've been searching on this issue for a while, and I wanted to see if anyone else was having similar issues and/or if there were any fixes.

Any time I open a particular Excel sheet (.xlsx format), I get the File Reservation window (the one that says "[This excel] is being modified by [Another User]. Open as Read-Only, or choose Notify to be alerted when it is available.")
The issue being that: *I* opened the file under that username, X days ago.
Some flag seems to be getting tripped that I can't remove, so Excel always thinks that this file is open and someone is editing it. This might not seem like a big problem, but the thing is I'm not the only one who can edit this file, so I can't just assume that no one has edited it since me, so any time I make changes, I have to save a new version. This amounts to many copies of this file, which is unnecessary and annoying to maintain.
Is anyone else seeing this issue? Is there a flag somewhere that I can remove?

If it's only affecting this one file, it might be worth recreating the file and deleting the original. If it's affecting multiple files, then it might be a permissions issue with the directory itself.

False File Reservations Fix

If you open Terminal and go to the folder where the file is located, enter "ls -la" and you'll see that there is a file with the same filename preceded by a tilda and dollar sign"~$". Delete that file and your problem is solved.

Use the following: rm "~\$filename" to delete the file.