Apparently you are not familiar with Art. V if you missed the parts about conventions. Constitutional conventions, either federal or state, may use direct democracy as the means of decision-making. Thus, the people can vote on constitutional amendments, and indeed to toss out and replace the entire Constitution.
As for the rest of your response, you have a fixation on your bizarre claim that the U.S. is not a democracy. This is both incorrect as a matter of definition, see Phoenix Dragon’s post, and as a matter of practical usage. Words having the meaning ascribed to them by those who use them. And, in the United States, “democracy” is the term used by the overwhelming majority to describe our system of government. Hence, the United States system of government is a “democratic” system of government.
You obviously have problems with the type of democracy exercised here. Fine, have at it. But the use of the term “democracy” to describe the US government isn’t open to debate. It is, just as Mount Everest is, and Al McCoggin isn’t.
Sua