I've had this issue on an old donor engine I bought.
So there is no ceramic left in the remainder of the plug, it's dropped into the cylinder?
Well you can't run the engine with ceramic in it, it'll damage your valve seats. You must have snapped it off quite low down to do that.
However, if there is no ceramic in the middle of the plug, it's a lot easier to drill out and then in theory you might be able to insert a tube into the hole and hoover out any bits. Someone will probably tell you you can do that with the engine in situ, but it's a pig of a job. For me it's an engine out job, but not an engine rebuild, just some drilling.
If there is still ceramic in the middle of the plug, it's impossible to drill. sometimes you can blow it out the top of the plug just by running the engine, Then you just need to reverse drill out the remainder of the plug. Else punch the ceramic down into the engine and follow step one.
Personally, I would pull the engine out, which can be done with basic tools, you just need a big socket for the sprocket nut, trolley jack and a Haynes manual. and hope your exhaust studs are in good nick, but no dramas, you're pulling the engine out anyway.