If they are steel, and it sounds like they are, I would not leave them, they could start to degrade and plug something up, see if you can drill a small hole in them being careful not to hurt the cylinder, and get a slide hammer with the lag type dent puller attachment, you will probably have to hold the spent plug with a pair of vise grips to get it to thread, then just bang it out.
I know I know, its eaier to write it then to do it, but I think you will be OK.
Best of luck! that sucks...