freebsd stable - May 2018 - zpool remove issue

Hello.

11.2-BETA3

# zpool remove zroot diskid/DISK-MN1220F32J32MD
cannot remove diskid/DISK-MN1220F32J32MD: root pool can not have
removed devices, because GRUB does not understand them


But I don't have GRUB and my boot device is on another pool.