Thanks for sharing that. I’ve always just repotted stuff in a slightly larger pot, but eventually the pot gets bigger than I want. Just never though about pruning the roots before.
I know most pots are round but when root pruning think of a square. Get your plant out of the pot. Cut halfway between the top and bottom then cut off the sides to make a square. Fill your pot with enough fresh soil (my mix is 3 parts soil 1 part manure) so that when you put your plant in it is near the top of the pot, then fill it in with your mix. I have a small saw I use just for pruning.