Removing a seat post spacer
It’s much easier to push than it is to pull. 

So I suggest you remove your bottom bracket entirely and then push the spacer all the way down into the bottom bracket space where it can be then cut, folded, spindled, and mutilated. 

Appropriately sized wooden dowels or PVC tubing would be your best bet if you didn’t want to mar the seat tube. Very long handled minus screwdrivers can be used if you don’t care anymore. An aluminum spacer may have cold welded itself to a steel seat tube and in those cases, chemical or thermal assistance may also be needed. 

Ps. I don’t actually see a seat post clamp on your bike in your pictures and so I’m assuming you do actually have one.