Via the Fitbit Wallet section of the Fitbit app

You can remove or suspend the card added to the smart watch using the Wallet section of the Fitbit app. You can still make payments using your physical card. No-one else can use your smart watch to make a payment without first entering your Fitbit 4-digit PIN code.

Via the Fitbit Website

If you have also lost your mobile phone, you can log into your fitbit.com dashboard on a computer to delete any cards added to Fitbit Pay.

If you are having trouble removing your card, you should contact us on 1300 747 747 to request that your card be disabled for use with Fitbit Pay