I haven't done this, so this is theoretical advice. YMMV.
You might try (carefully) turning a long drywall screw into the white thing stuck in the head and then pulling back on it. Or a long wood screw -- something with nice, wide threads.
The injectors themselves may be salvageable. Those three parts at the bottom (white pintle cap, brown o-ring, and orange spacer) are all replaced in a normal injector cleaning. So as long as the injector bodies themselves are ok, you may be fine. Once you get the third injector out, you can send them all to mrinjector.us, or similar shops, for inspection, cleaning, and new seals etc. Mr. Injector just did mine and has done many others with lots of thumbs-up.
Refurbished injectors are also pretty widely available from those same shops, and on eBay. (In this case, "refurbished" basically just means cleaned up the same way they'd clean yours if you sent them in.)
For that last injector, maybe you could get a vise-grip or pair of channel locks onto the top of the metal body (not the white plastic at the top), and rock it back and forth a little to loosen it up.
And lastly... there's undoubtedly a bunch of gunk in those injector holes, which you'll want to clean out once you get them clear, and without letting crud fall into the head. My tip on this: When I cleaned them out after removing the injectors, I took the shop-vac, with the smallest detailing nozzle I had, and held it right next to the hole while I swabbed the muck out with q-tips moistened with mineral spirits. The mineral spirits did a great job of removing the crud, and not a problem if a little drips in; it'll just burn up. Holding the shop-vac nozzle there helps draw any loosened bits upward, rather than letting them fall into the head. Come to think of it, you might even want to do that before removing the stuck caps and o-rings, as those will help block other stuff from falling down in.