Reset change login user name password for nextcloud in a very simple way
First click the password reset link on the login screen; this appears after a failed login attempt. This works only if you have entered your email address on your Personal page in the Nextcloud Web interface, so that the Nextcloud server can email a reset link to you.
Now ask another Nextcloud server admin to reset it for you.
If neither of these is an option, then you have a third option, and that is using the
occ command. See Using the occ command to learn more about using the
$ sudo -u www-data php /var/www/nextcloud/occ user:resetpassword admin Enter a new password: Confirm the new password: Successfully reset password for admin now try to login using local host or on your System IP http://localhost/nextcloud