I have taken links apart on a couple of chains with a cheap ryobi grinder, just keep drinding till its flat and you see the outline if the pin, it's not like your going to harm anything, don't be afraid just giver
View attachment 104870
View attachment 104871
View attachment 104872
place the chain over the nut and if you put the pin in the right spot on top of the nut then give it a good hit with a decent hammer (not dollar store) or a baby sledge hammer (not dollar store either).
Once you get the pin starting to come out either dubble up on the nut underneith the chain or use some pliers or vice grips to pull it out the rest of the way.
I was going to buy a chain breaker a couple of years ago but the ryobi grinder have been used hundreds of times where as if I bought the chain breaker I would of used it about 4 or 5 and good chain breakers are not cheap.