Protect my slides. Make my PowerPoint file non-editable

I am running a presentation design firm and hence I get to make various kinds of presentations for my clients across the world. Recently a client for whom I am making an investor pitch deck posed this question. He runs a startup in Silicon Valley.

SP: "I do not want my audience to take my slides and use them. They should not be able to edit my slides at all. How do I do this?"

Well, the answer turned out to be quite simple.

Go to File --> Save As --> Tools (look to the left of Save) --> General Options --> Enter a password to modify.

When people open the slides, they have 2 choices. View the deck 'Read Only' or enter the password. If they choose Read Only, they will not be able to make any changes to the deck. They can only view it.