Como limpar chroots do Ubuntu SDK?

Question

Eu tenho muitos chroots criados pelo Ubuntu SDK, montados automaticamente no boot:

$ 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

Existem 16 no total, 8 para armhf e 8 para i386, todos com o mesmo nome. Além disso, iniciar o Ubuntu SDK cria mais 2 (18 no total), mas o fechamento remove-os (de volta a 16).

Os outros 16 chroots são alguns restos? E se sim, como removê-los?

Eu vi essa outra pergunta, removendo o chroot feito pelo ubuntu touch sdk , mas acho que meu problema é diferente, porque tenho muito mais pontos de montagem e, em /etc e /var/lib , tenho apenas um par:

$ 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