turning off the two factor authentification

From the article below updated on 22 Jan 2020. If it has been on longer than 2 weeks, you can't turn it off. 

Can I turn off two-factor authentication after I’ve turned it on?

If you already use two-factor authentication, you can no longer turn it off. Certain features in the latest versions of iOS and macOS require this extra level of security, which is designed to protect your information. If you recently updated your account, however, you can unenroll for a period of two weeks. Just open your enrollment confirmation email and click the link to return to your previous security settings. Keep in mind, this makes your account less secure and means that you can't use features that require a higher level of security.

Apple ID -Two-factor authentication.       

You are welcome.

I don't think so.

https://en.wikipedia.org/wiki/Dropbox_(service)

DropBox Inc is an independent company. It was founded by a couple of MIT students, but it is now a publicly traded company.