You will need to erase all registered phone numbers and devices.
If you cannot receive the SMS challenge on the current mobile phone or if you don't have access to your mobile phone number anymore, please use the PANIC button (STOP) and then register the new number/device.
This action does not require you to be logged in with the 2-factor and will remove from your account all the mobile phone numbers/devices that were associated to it:
-Login via https://webgate.ec.europa.eu/cas/userdata/myAccount.cgi with your email address and your password (please use "Password" as authentication method).
-Select the option "Delete all my devices and eID (PANIC)". The PANIC button is only available for external self-registered users and is visible once there is a registered 2-factor method (mobile device or mobile phone number or any other method).
-A message appears. You can confirm by clicking on "Delete".
-There is a confirmation message. The system will automatically log you out.
You will then be able to register a new mobile phone number/device following the instruction on page12 to add your mobile device ( to enable the "EU Login Mobile APP PIN code" or "EU Login Mobile APP QR code" method ) and page16 to add your mobile phone number (to enable the "mobile phone + SMS" method) here : https://webgate.ec.europa.eu/cas/manuals/EU_Login_Tutorial.pdf