Website data is it safe

When trying to sign Into my Yahoo account on my new android device I was asked to allow cookies on the server that is on my iphone se 2nd gen along with my password/passkey to my yahoo account and when trying to do that I was told to go to advanced settings and the cookies were allowed then somehow I got on the page where I saw for the first time all these .com places with abrieviations that I didn't understand and some of them had me worried. So now I'm here and my question is should I delete them all or will it hurt phone and will I lose valuable information ? Please will someone let me know 🙂