To lock your Facebook profile, you can use the desktop app or mobile app.

To lock your Facebook account on a desktop, log in to the Facebook account and click on “Account Settings.” You will see an option to “Lock Account” or “Set Time Limits.” If you select “Set Time Limits,” you will be able to set a time limit for different activities within your account. If you select “Lock Account,” you will be able to set a password and change who can access your account.

To lock your Facebook account on mobile, tap on the three horizontal lines in the upper right corner and then tap “Settings.” From there, scroll down until you find a section titled “Account Security.” Tap that section and then select “Lock Account.”