If you want to restrict access to a specific profile on your account, you can protect it with a Profile Lock PIN.
To add a PIN to a profile:
From a web browser, go to your Account page.
Open the Profile & Parental Controls settings for the profile you want to lock.
Change the Profile Lock setting.
Enter your Netflix account password.
Check the box to Require a PIN to access the selected profile.
To remove the PIN requirement, uncheck the box.
Enter four numbers to create your Profile Lock PIN. Unless you're using an unsupported device, you will enter this PIN to enter the profile or play titles downloaded from it.
If you want to require a PIN any time a new profile is added to your account, select Require PIN to add new profiles.
If you forget your Profile Lock PIN, click the Forgot PIN? link on the bottom of the screen. If you’re watching on a TV, enter the provided web address into a web browser.
To view or edit the Profile Lock PIN that was created for the profile, enter your Netflix account password.