Just in case link doesn't work:
https://imgur.com/a/asd-41a5VpX
English
#Help
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Hi there, Thanks for reaching out! Players who entered an incorrect Date of Birth can update their information from their settings page on bungie.net, found by clicking the profile picture in the top-right. If you're unable to do so, please submit a ticket by using our Privacy Contact Form and selecting the “Correct My Data” option. https://help.bungie.net/hc/en-us/articles/360049024632