Genuinely curious - which model is this? I bought a LG C2 OLED last year (still current model) and never experienced this. It mentioned alexa support on the box, but I have never seen any popups related to it.

FWIW - on most LG TVs, you can 'revoke' your acceptance of the EULA, which essentially returns the TV to non-smart status. Most of the tiles will disappear from the home screen, as will the ads. Depending on the model you might need to futz with the settings to make sure that the TV defaults to the hdmi input instead of the homescreen when you turn it on.