Clean up or edit the accounts on your iPhone (iOS 13) by looking under Settings > Passwords & Accounts. This allows you to see what accounts reside on your iPhone, such as iCloud and Gmail. You can add new ones or delete accounts that you don't need anymore. If you have a malfunctioning auto-login process, such as one your workplace set up for you, you may want to delete the account and re-add it after consulting your IT coworkers. Random pop-up error messages can get quite annoying, after all.