Being always on-par with the technological progress of security mechanisms, Zyxel offers also Two-Factor-Authentication (2FA) on the myzyxel.com - related portals. However, the time might come where you want to disable this feature.
In order to disable Two-Factor-Authentication, you need to login to the portal.
From there you can disable 2FA.
Log in to MyZyxel (https://www.myzyxel.com/)
Access "Account" on the very top right of the page.
Go to Two-Factor Authentication page and select disable, then apply.
After applying the changes should Two Factor Authentication be disabled on your account.