Because you edit config and try to disable “site”. My NC config was in sites-enabled and your in conf-available.
→ Everything under *-available is something that you could use, but it is not.
→ Everything under *-enabled is something are using now.
Check your folder /etc/apache2/sites-enables/there should be something like 000-default.conf this is your site configuration. It could be that nextcloud.conf is also there, then run a2disconf nextcloud.conf. My Site config example was listed here:
Only difference that you have to comment to get it A+:
Alias /javascript /usr/share/javascript/
Alias /nextcloud /var/www/nextcloud/