2.4. Unmounting a Hierarchy

You can unmount a hierarchy of cgroups with the umount command:
~]# umount /cgroup/name
For example:
~]# umount /cgroup/cpu_and_mem
If the hierarchy is currently empty (that is, it contains only the root cgroup) the hierarchy is deactivated when it is unmounted. If the hierarchy contains any other cgroups, the hierarchy remains active in the kernel even though it is no longer mounted.
To remove a hierarchy, ensure that all child cgroups are removed before you unmount the hierarchy, or use the cgclear command which can deactivate a hierarchy even when it is not empty — refer to Section 2.12, “Unloading Control Groups”.