#!/bin/sh

umount /usr/loacal/jails/devuan/dev
umount /usr/loacal/jails/devuan/dev/fd
umount /usr/loacal/jails/devuan/proc
umount /usr/loacal/jails/devuan/sys

sed -i '' '/devuan/d' /etc/fstab

kldunload linux
kldunload linux64