That button can be reduced in the settings of the theme.Dawn theme is a free theme, why don't you upload a Premium Theme to enhance your store layout and look?

Oh I see. Adding a phone to your account isn't compulsory on Shopify. The major is your email and strong password.I'll just advice you leave that for now. In as much you have a strong password with email, then your Shopify admin account is safe. You ...

Have you tried using another number to test?You can as well leave it for a day or two, then login on your browser,  then give it a shot again.