How to clean cache?

I have some files in my cache directory (chunk files) and some entries in oc_filecache. I would like to know the best way to clean that ?
Files in cache folder can't sync on Windows Desktop Client.
My config is ownCloud 9.1.6 on Raspbian Jessie Lite last version.
Thank you !

Just had a search at the github bugtracker and stumbled over the following. So you should NEVER EVER touch oc_filecache as this is no cache but an index of all your files and mandatory for the operation of ownCloud.