How do I sell a tank?

It's easy to sell your tank. Tap on the tank you want to sell then say upgrade(you will find that at the top of your screen to the right where it says battle)then tap tell (at the bottom right corner)

In the garage, select your tank, select the research panel, there you can select to sel the tank.
That's it....
Simple...

Select a tank, then click on upgrade button. You will see sell button on bottom right side of the screen.

You have to go to the upgrade thing the right under the screen there,s a red button named sell you click and boom selled