Well RJ,the only way that you are going to remove the seams is by first masking off the clear polished areas with masking tape,then rubbing down the seams carefully using plenty of water,plus a small piece of fine wet and dry paper,go careful otherwise you could easily go through the tape itself.
Best to cover the entire canopy in tape first,even two layers,then carefully with a small blade cut the seams clear,you could try scraping the seams which should work,then finish off with the wet and dry paper.
Place a lump of Bluetak inside the canopy and plunge a piece of dowel into it,this will assist holding the canopy while you work on it,but go careful,and work slowly.