Not sure if anything is actually needed. It just looks unstable. Power is already run to the shed, so it might be difficult to move and do a full concrete pour. I was thinking of lifting with a car jack and finding a better combination of pavers to remove the wood wedges, but I'm open to any ideas. And it is on a slope, the other end is on pavers on the ground. This stack of pavers was the previous owners attempt at levelling I guess.
Empty it out, roll it from its spot with some logs neolithic style, grade the area properly, then roll it back.
PVC pipe would work as well. The larger the diameter the better.