This a job where having the service manual or having someone show you how to place the gas tank pivot bolt in the MAINTENANCE POSITION will keep you from cutting or tearing the joint hose that connects the upper and lower fuel tanks. If you remove the two front retaining bolts and just lift the tank you likely will cut that hose and dump a gas tank of gas on the ground.
You remove the two retaining bolts, remove the seat, set the seat height adjuster in the middle position, loosen the horizontal pivot bolt under the rear of the upper tank, then slide the tank fully back before lifting it. In doing so the tank moves back as the horizontal pivot bolt slides in a track about 2" back to the MAINTENANCE POSITION. You must do this before lifting the tank - this gives the joint hose enough slack to avoid cutting or stressing it when the tank lifts.