我有许多由 Ubuntu SDK 创建的 chroot，它们在启动时自动安装：
$ df -h
Filesystem Size Used Avail Use% Mounted on
udev 1,9G 0 1,9G 0% /dev
tmpfs 375M 6,0M 369M 2% /run
/dev/sda1 20G 18G 1,3G 94% /
tmpfs 1,9G 172K 1,9G 1% /dev/shm
tmpfs 5,0M 4,0K 5,0M 1% /run/lock
tmpfs 1,9G 0 1,9G 0% /sys/fs/cgroup
/dev/sda5 79G 21G 54G 29% /home
tmpfs 375M 8,0K 375M 1% /run/user/118
click-ubuntu-sdk-15.04-armhf 20G 18G 1,3G 94% /var/lib/schroot/mount/click-ubuntu-sdk-15.04-armhf-1c9c9d5d-47c9-4474-bfdb-bd4ba7a0454c
click-ubuntu-sdk-15.04-armhf 20G 18G 1,3G 94% /var/lib/schroot/mount/click-ubuntu-sdk-15.04-armhf-2998687b-35bd-4052-b850-6741a1ff793b
click-ubuntu-sdk-15.04-armhf 20G 18G 1,3G 94% /var/lib/schroot/mount/click-ubuntu-sdk-15.04-armhf-757db6e4-3e26-4b9b-b916-b4847c39ce82
click-ubuntu-sdk-15.04-armhf 20G 18G 1,3G 94% /var/lib/schroot/mount/click-ubuntu-sdk-15.04-armhf-83d28a49-7e9b-42fb-a296-c8c3d5fa6877
click-ubuntu-sdk-15.04-armhf 20G 18G 1,3G 94% /var/lib/schroot/mount/click-ubuntu-sdk-15.04-armhf-b2ac117d-c2b6-4979-9ba1-f880611eefbb
click-ubuntu-sdk-15.04-armhf 20G 18G 1,3G 94% /var/lib/schroot/mount/click-ubuntu-sdk-15.04-armhf-bc49e90d-aba7-4af8-9584-32a3d0735e91
click-ubuntu-sdk-15.04-armhf 20G 18G 1,3G 94% /var/lib/schroot/mount/click-ubuntu-sdk-15.04-armhf-beb90580-6569-4efc-b757-8e50febc2aa0
click-ubuntu-sdk-15.04-armhf 20G 18G 1,3G 94% /var/lib/schroot/mount/click-ubuntu-sdk-15.04-armhf-ucca-1000-{bd08aa0c-a667-4bad-853b-80e347c96356}
click-ubuntu-sdk-15.04-i386 20G 18G 1,3G 94% /var/lib/schroot/mount/click-ubuntu-sdk-15.04-i386-205a6f84-56f4-4878-823e-45991d0bad19
click-ubuntu-sdk-15.04-i386 20G 18G 1,3G 94% /var/lib/schroot/mount/click-ubuntu-sdk-15.04-i386-2dab8b44-ec72-41b5-bf56-4a7c391ca051
click-ubuntu-sdk-15.04-i386 20G 18G 1,3G 94% /var/lib/schroot/mount/click-ubuntu-sdk-15.04-i386-5bd09d98-e3df-4ee7-9aef-b6c0823aea4d
click-ubuntu-sdk-15.04-i386 20G 18G 1,3G 94% /var/lib/schroot/mount/click-ubuntu-sdk-15.04-i386-814277af-39ca-49db-9453-ec676de3371e
click-ubuntu-sdk-15.04-i386 20G 18G 1,3G 94% /var/lib/schroot/mount/click-ubuntu-sdk-15.04-i386-a8e8dbca-e99f-4ad8-98bb-a58f2367786b
click-ubuntu-sdk-15.04-i386 20G 18G 1,3G 94% /var/lib/schroot/mount/click-ubuntu-sdk-15.04-i386-c265898a-bd46-49fb-995c-b0461ba97797
click-ubuntu-sdk-15.04-i386 20G 18G 1,3G 94% /var/lib/schroot/mount/click-ubuntu-sdk-15.04-i386-e379e1b6-2474-40a5-9061-0aef4334a038
click-ubuntu-sdk-15.04-i386 20G 18G 1,3G 94% /var/lib/schroot/mount/click-ubuntu-sdk-15.04-i386-ucca-1000-{e3fee6a2-a29c-4438-af77-60ae209c8a60}
tmpfs 375M 40K 375M 1% /run/user/1000
总共有 16 个，8 个用于 armhf，8 个用于 i386，所有名称都相同。此外，启动 Ubuntu SDK 会再创建 2 个（因此总共 18 个），但关闭它会删除它们（回到 16 个）。
其余 16 个 chroot 是一些剩余的吗？如果是，我该如何删除它们？
我确实看到了另一个问题，ubuntu touch sdk 删除了 chroot，但我认为我的问题不同，因为我有更多的挂载点，并且在/etc和中/var/lib我只有一对：
$ mount | grep schroot | wc -l
313
$ ls /etc/schroot/chroot.d
click-ubuntu-sdk-15.04-armhf click-ubuntu-sdk-15.04-i386
$ ls /var/lib/schroot/chroots
click-ubuntu-sdk-15.04-armhf click-ubuntu-sdk-15.04-i386