Cleaning/clearing/deleting updates in WSUS and re-synchronising - Server 2012 R2

I mistakenly selected a number of products for update when configuring the upstream WSUS server. When I then synchronised the downstream server with this upstream one it still took all of the mistakenly downloaded updates. I had changed the product settings on the upstream server to only get Windows 8 and Server 2012 updates and run the sync again before this. No updates have been applied/installed.

MY QUESTIONS:-

1. Can I delete all the updates on the upstream server and then re-sync this upstream server with Windows Update? How?
2. Can I then delete all updates from the downstream server and re-sync it with the cleaned upstream server?

Thanks for any help...