To disconnect your  Promo account from Facebook, please go to My account and click on “Disconnect from Facebook” button. 

In case you did not have any e-mail address connected to Facebook, the system will ask you to add login e-mail and password. Then click on "Save changes" and Facebook will be disconnected:

If you have e-mail address connected to your Facebook, after you click on “Disconnect from Facebook” button, Facebook will be disconnected immediately, and you will be able to reset your password at https://promo.com/forgot-password

If you need to change your  email address, you can do it on  My account, page as well.