Major revision and re-submit as a Technical Note I submitted a manuscript as a Research Paper last May 12 to Journal A. Now, 6 months later, I have received a decision letter recommending "... undertake a major revision, and re-submit a revised version of your paper as a Technical Note". Talking with co-authors we disagree and would like to submit the paper to a different journal (Journal B). What should I do? Should we submit the paper to Journal B if it is still "under revision" in Journal A? I have sent a letter to the Editor of Journal A, explaining that we'll not re-submit the paper as a technical note, but I have not yet received any reply. 
Thanks for the advice!
To make it clear to the editor, formally withdraw it from consideration. Then it is yours to do with as you please. They have no hold over you or the paper until you formally sign copyright away. What you have sent is likely enough, actually, but a formal notice of withdrawal leaves no ambiguity. 

In most places I think that giving notice is enough and their reply isn't needed. But you need to keep records. Formal mail (sneaker net) with a receipt for delivery is sometimes used for such things. And keep the receipt.