I am using my nextcloud as a family communication center. I set up a mail server, but everybody wants to use their email accounts. How do I disconnect the mail server and enter the new email information? What I am, in effect, asking is how do I get to the “connect to your email account page” again.
Try reviewing some of these previous topics in case they help.
https://help.nextcloud.com/search?q=change%20user%20email
Email admin documentation
https://docs.nextcloud.com/server/latest/admin_manual/configuration_server/email_configuration.html