I believe if you combine the delete by query with a match all it should do what you are looking for, something like this (using your example):
curl -XDELETE 'http://localhost:9200/twitter/tweet/_query' -d '{
"query" : {
"match_all" : {}
}
}'
Or you could just delete the type:
curl -XDELETE http://localhost:9200/twitter/tweet
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