@vapre
At the moment, it's not possible to remove your authenticator app as a second factor for a 1Password account. Historically the reason for this was because not all of our client apps supported Security Keys as a second factor so it was still necessary to enter a six-digit code from a user's authenticator app in order to add a 1Password account to those client apps.
However we've now added the ability to use Security Keys are a second factor to all of our client apps and that sets the foundation for us to be able to offer users the choice to only use a Security Key as their second factor. I don't have any public-facing information on when and if this work will be completed but I can confirm that it's something that our developers are looking into.
For the moment, if you'd like to avoid using an authenticator app you can print the TOTP secret to keep with your Emergency Kit (as a backup) then delete the Authenticator app from your phone once everything is configured.
-Dave