I went through this a couple of weeks ago when my pump failed. Here's what I did.
My pitless adapter is about 3ft down from the well cap. I bought a 10ft stick of 1" black pipe at Home Depot and had them cut it into 1 7ft piece and the leftover 3ft piece cut in half. I put it together with a 1" tee fitting and bought some 1" end caps to prevent cuts on my hands.
Once I had it screwed into the top of the pitless adapter, I could not push/pull it up.
I laid a piece of plywood next to the well cap and brought out my floor jack. Along with a scrap piece of wood, I jacked up on the bottom of the tool until the pitless finally dislodged.
You'll have to be careful as the whole thing will try to rack as you're lifting the jack. Ideally, you'll have someone to keep everything lined up while you work, but I did it myself in a moment of impatience.
Hope that's clear and that it helps. If not, let me know and I can try to explain further.