1) If you have a Presentation like below and need to send it somewhere it will need protecting, the easiest way to do that is to password protect it.
2) Go to File.
3) Click on protect presentation.
4) Click on encrypt with password.
5) Enter password and click OK.
6) Re-enter the password you have just set and click OK.
7) It should now show the presentation as protected, you must save it to ensure the change.