Pull the posts. Use an old-fashioned automobile jack. The kind with a 3’ or 4’ rack gear standing vertically and a long lever to jack the shoe up and down. Hang a cast steel chain hook from that shoe. Use a web strap to wrap the post and hook to the chain hook. Put a 2X4 between the post and the shoe to protect the vinyl post. Put a stack of three 2x8’s under the jack so you jack the post out rather than draw the jack into the ground. Use three so they don’t snap in two under the jack. This works. I pulled around (40) 8" wood posts this way. Slow but not too dangerous.
Then rent a one man post hole digger. One with two power driven wheels and the engine hanging out in front of those wheels. The auger is in the rear, by the handles. You pull down to dig. It can’t get away and spin around throwing you off. I ran 120 holes in three days with one. Drilled in heavy clay, roots, tile (oops), whatever. Drill a hole, drive it to the next one, drill again. They don’t even rent the old style augers with one or two handles around here anymore.