I'm nervous every time a curious friend picks up my iPhone and ventures into Settings—not because they could see something they shouldn't, but out of fear they might mess up my multiple email accounts.
While removing email accounts from an iOS device won't wipe the server, re-adding them is a tedious process: you need to remember your access credentials and, if an account is protected with two-factor authentication, provide a verification code, too.
iOS lets you disallow changes to some device settings, including restricting all email, calendar and contact accounts so that no one can add or remove them, here's how.