Need to disable 2FA on account

Question

So my friend has a small business account, and somehow 2 factor authentication got turned on for his account, so when he tries to login to office.com or open outlook on his computer, he is getting prompted for a code. He never installed the microsoft authenticator app, so can't generate any codes. He can't access e-mail since it is prompting him for that code - he knows the password to the account (it is long and fairly complex), so I doubt his account has been compromised. Is there any way to turn off the 2 factor authentication? The agent at Help.microsoft.com directed us to post here in the forum as it is the only place to get help (which seems odd) -