for subvol in ${s[@]}; do btrfs subvolume delete /mnt/$subvol; done
btrfs subvolume set-default 0 /mnt
[[ ! -e /mnt/root_$DISTRO ]] || btrfs subvolume delete /mnt/root_$DISTRO
for subvol in ${s[@]}; do btrfs subvolume delete /mnt/$subvol; done
btrfs subvolume set-default 0 /mnt
[[ ! -e /mnt/root_$DISTRO ]] || btrfs subvolume delete /mnt/root_$DISTRO