If you need to get under the tank of a Ducati Monster there is a few steps. Try to do it before you fill up! This Vid shows how to remove the tank the quickest way, which I needed to do to get to my exhaust but if you want to get to the battery you need to follow these steps as well.

I recommend once you have done this once, have the right sized Allen keys x 2 in your tool bag under your seat!! If you break down and need a jump start, you will need to know these steps to get to the battery!! Even better, practice removing the tank at home one day, just so your familiar with how to.