Change the options in the mntent section. If you edit the pool in the web interface, it will add them back though. I guess I could add a checkbox to disable them.
Is this something that can be implemented in the near future? Namely remove all the "x-systemd.requires" options from the union pools entry in fstab. And maybe a reload/check function for mergerfs so that all branches shows correct disks and not n/a without the need of modify mergerfs?