MobiOffice lets you protect your Presentation on a file level, allowing no one to view the file, unless they have the password.
Password-protect a Presentation
1. Open the Presentation. Tap the menu in the top right. Tap Protect.
2. Enter and confirm the password.
3. Tap OK, then Save/Save as the Presentation.
Remove the password
1. Open the Presentation. Tap the menu in the top right. Tap Unprotect.
2. Enter the password.
3. Tap OK.