You can delete your account anytime you want. Do note, however, that all your data will be lost after 7 days and you won't have the option of retrieving it if you don't export it.

To delete your account, perform the following steps:

From the Withings App:

1. Go to Profile.
2. Tap the gear icon, then Profile. 
3. Scroll down and tap Delete my Account.
4. Confirm you want to delete your account by tapping Yes.

From the online dashboard:

1. Go to the online dashboard.
2. Click your email address in the top-right corner and click Settings.
3. Click the User tab.
4. Click Delete user.
   The user management screen is displayed.
5. If you have several users and want to make them independent, click Make independent.
6. If you have several users and want to delete them as well, click Delete.
   Make sure you delete all secondary users before trying to delete the main user.
   If you change your mind at this stage, simply click Reactivate.
7. Click Delete account.
   At this stage, you have the option of exporting the data of each user by clicking Download. Make sure you do it before all your data is lost.
   If you change your mind at this point, you can also click I don't want to delete my account. Take me back!.
8. Click Delete my account.