How to purge DeviceMapper backend used by Docker

Hello All,

I have Docker 1.10.3 on RHEL 7.2 server with the following storage options:
DOCKER_STORAGE_OPTIONS="–storage-driver devicemapper --storage-opt dm.fs=xfs --storage-opt dm.thinpooldev=/dev/mapper/dockervg-dockerlv --storage-opt dm.use_deferred_removal=true --storage-opt dm.use_deferred_deletion=true"

So I’m using DeviceMapper as a backend as follow:
[toto] # lvs --all
LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
dockerlv dockervg twi-aotz-- 99.84g 98.15 68.26

How to purge the thindevice pool ? My the sum of my images and dockers don’t exceed 10GiB.
N.B: I already used docker-gc of spotify, it doesn’t help that much.