Once created, the global stream of changes, a.k.a the hose will start to be indexed into elasticsearch (including all the relevant metadata, like geo location, places, replies, and so on). Think about the power and capabilities you get with all that data indexed in elasticsearch ;).
Deleting the twitter river is as simple as:
curl -XDELETE localhost:9200/_river/my_twitter_river
The twitter river will be provided as a plugin in 0.11, and can be easily installed using
plugin -install river-twitter.