I need to cut several stitch welds to remove some casters off the bottom of a cart. I used an angle grinder to cut some of them. I then switched to a mini die grinder to get in some tighter spots; that grinder was very weak. But I still need to remove some more.

The picture shows the tight spot they are in. I cannot get a grinding disc in there and I cannot get a sawzall blade under the caster base.

Can I bust them out with a cold chisel?

I did some reading on arc gouging and plasma cutting but I don't want to buy that kind of equipment just yet.

One post I researched mentioned using a stick welder turned up high and using a conventional rod to melt the weld, and letting gravity do the rest. I have a Thunderbolt AC/DC. Can I do this with the supply of rods I have on hand (I do not know what they are; they came with a welder)? Or do I have to buy some special kind of rod?

Please provide instructions on how I should do this, or point me in the right direction.