@chesjak34
That sounds like a question for your network administrator (assuming you're asking about something at work). I don't think Excel per se can be locked. But access to any of your files is something you or a network admin should be able to control, but it's not an Excel question.
If you're talking of your home computer, that too is another question. I've never even worried about it, because my files are secure from prying eyes, including those in the cloud (OneDrive, iCloud). I can grant access to selected people, and have done so, but unless I do they're secure.
So unless you've got some unusual circumstances, I'm pretty sure you've come to the wrong place. Maybe you could say more about the sources of your concern.
