To protect PowerPoint presentation file from other people to open and edit it except those who know the password, there is a protect presentation section in PowerPoint 2013 where you can apply password to the file (.pptx). In this guide you will learn how to password protect PowerPoint presentation file or Mark as final that will let other people know this file is final no need to make any changes.
Password Protect Presentation File
When you apply password to presentation file then every time you open the file, have to enter password. If you forgot password there is no method given by Microsoft to recover or remove it.
Open your presentation which you want to password protect. Click on “File” tab top left corner of the “Ribbon”, and then click on “Info” tab. Now click on “Protect Presentation” section and click “Encrypt with Password” from drop-down menu.
A Encrypt Document “dialog box” will open and you will be asked to enter the Password, Renter password for confirmation and click on “OK”.

Note: Microsoft will not help you to retrieve or remove your forgotten passwords.
Remove Password from Presentation file
If you no longer want to apply password restriction to the presentation file, to remove your password,
open the password protected presentation file enter password and click on “File” tab > Info > “Protect Presentation” and select “Encrypt with Password”.
A “dialog box” will appear, there will be a password in the box, delete it and click on “OK”button.
Mark as Final
Mark as final is just a message to the person who open the presentation file, that this file is marked as final and no future editing of modifications are required.

Select the option “Mark as Final from where you access the password option above. A dialog box will appear promoting you to save. Click “OK”.