I like non-toxic Citrex, you can get this at Walmarts and diy stores. Just follow package directions.
Here's a video tutorial: https://www.youtube.com/watch?v=bV74s1zo4a0
You can remove the finish with mineral spirits or a deglosser.
Citristrip is a good stripper than you can live with the scent if you are working on this indoors.
Whatever stripper you use, make sure you let it cure according to the directions because if it dries that is a big mess.
Make sure to protect your floors underneath.
I used a plastic scraper when I did mine. Scrape in the direction of the wood grain.