Add the capability to remove a root dir

[rajubairishetti]

Currently, we can add a new rootdir to the consumer and also remove rootdir which is at the end.
Checkpoint is not valid, if we have to remove a rootdir which is not end of the list.
This is because the clusterid is calculated as the position of the rootdir in the list.
We can define a meaningful clusterid than the number and use it. Also, the solution here should honor the old checkpoint as well.