Not sure if you have tried this, but finish all the running workflows
don't trigger any new ones for some time and block all external excess
to your server.Now, go to http://:/crx/explorer and then make
a note of following node /etc/workflow/instances/server0, take a note of
all properties on your server sling folder node and delete it
using crx/explorer view. You can also delete date folders one at a time
or delete the parent node which is server sling
folder.Considering the number of the nodes...