Start by navigating away from your “Home” timeline area on Facebook back to your “Profile” Timeline, just click on your profile name top right of your Facebook home page. Then go down to just under your cover picture Click “About”
Scroll down to “Contact And Basic info” in the left menu, go across right to “Basic Information” and hover your cursor far right of your Birth Date and/or Birth Year and click the edit button .

Here you can change the birth date or set it to “Your Friends” Or “Me Only” to hide it from sight.

Note: You can also only show friends your birth date, (not the year of birth) if you wish them to send you a happy birthday wish on your birth date.
On Minor (under 18yrs) accounts the options are restricted only to friends and friends of friends.
NOTE: many children faked their birth dates to get an account on Facebook before they were 13 yrs of age. So check your child’s birth year on Facebook and be sure it is set correctly for their age, so that they benefit from some extra teen privacy settings. .
NOTE: many children faked their birth dates to get an account on Facebook before they were 13 yrs of age. So check your child’s birth year on Facebook and be sure it is set correctly for their age, so that they benefit from some extra teen privacy settings. .