Let's say you have this one last standoff. It's seized so go ahead and unscrew and it will unscrew from the case. Once out you can access both sizes to try to remove it. If you can't then cut off the threaded portion that would screw into the case and it will just be a standoff without the screw part.
Went over to a friend since he had trouble building his PC, realized he's used the wrong screws to screw in the motherboard and 4 standoffs went out as well as the motherboard. I managed to remove 3 of those with pliers but the 4th one is so stuck that half of it broke off while I tried unscrewing it. Any ideas on how I could remove it?

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