As explained during the certification process, your biometric data will be immediately deleted after your video has been compared to your profile pictures ; however, your video will be stored so your profile can be certified again if you happen to delete your pictures.
That being said, you can ask happn to have your video definitely deleted by going to My settings > My data > Manage my choices.

Note : if you delete your account, your video will be stored during a year along with the rest of your data, in accordance with article 6 of the Trust in Digital Economy Act voted on the 21st June 2004. For more information, please read our Privacy policy.