Remove the tank, if for no reason else than just to know how to do it. It takes less than five minutes and will make the job easier.
Set the petcock to "OFF" if it's not already.
Remove the seat.
Remove the two 8mm head hex screws holding the back of the tank.
Remove the fuel supply hose by loosening the clamp holding it to the petcock and pulling it free.
Remove the overflow tube from the bottom right side of the tank, about midway up. (Lift the tank just a little, look underneath, and it'll be obvious.)
Lift the tank backward and up.
Set it somewhere clever. I'd suggest on top of 2x4 chunks covered with rags to protect the paint. Don't rest it on the petcock. (I usually just lay mine on the ground, on the petcock, and no leaks yet, but I wouldn't recommend it.)
To reinstall, reverse the above steps. It's easier with a mostly empty tank.