How do I delete old data for old data inputs, and why is our receiver not receiving any data from our universal forwarder?

I created some remote data inputs which worked well. The documentation recommended using a universal forwarder for better performance. I deleted the old data inputs ok, but the data remains. How do I delete the old data? (we are doing the free trial, so just trying to work out the best way to do things. The old data is not important).