I have a desktop computer with 6 disks.
1 windows,
2 gentoo linux root disks in raid,
2 gentoo linux home disks in raid and
1 that varies over time.
I boot via refind that is installed on the windows disk.
On this last disk I installed GhostBSD.
After running it for a while I decided I would try install pure FreeBSD instead.
So I wiped the disk with wipefs from linux and installed FreeBSD over it on the whole disk instead.
But when I reboot and start FreeBSD it looks like GhostBSD, openrc and all.
So my question is simply where I can find and remove this GhostBSD that has hidden itself somewhere where I cannot find it.

Nevermind.
I discovered today that in order to remove zfs and install ufs it is not sufficient to use wipefs from linux.
Even if the install with the new ufs system went well, refind may find the zfs system and boot it event though the ufs system has been installed on the very same disk.
At least if the disk is large enough. And the booted zfs system reported that the pool was damaged.
dd from /dev/zero took some time, but fixed the issue and at least I learned something I didn't know before.

Guy Grinnell pointed out on t.me/ghostbsd that wipefs does not appear to be ZFS aware.Submitting a bug report might another means to solve the issue.

E-MAIL: util-linux@vger.kernel.org
Web: https://github.com/karelzak/util-linux/issues

Reference: https://git.kernel.org/pub/scm/utils/ut ... git/about/

The way I did this (needed to shrink it and also wanted to replace the Linux I had installed but needed a new partition) was boot from USB drive, import the ZPOOL, then destroy it. That’s technically the proper way per FreeBSD docs since it ensures metadata is removed (and is a lot faster than dd)

Also:

https://man.freebsd.org/zpool-labelclear(8)