To your question, I used a Dremel cut off wheel like shown below. It cuts through tubing in no time. You are left with a burr, but that is easily filed and then sanded flat. I eventually figured out that if I slowly rotate the tubing using my fingers whilst I cut, I can get a much cleaner edge. In short, less cleanup.
It’s a handy bit to have when working with metal. (Wear eye protection)