If you want to up pot a cloth bag type potter you can.
First take a bread knife and slide it around the out side of the bag. Use the back edge of the blade for the leading edge.
Second place the bag on a upside down plastic pot. The plastic pot should be slightly smaller than the bag bottom. Then fold over the cloth bags top edge. Grab the cloth bag edge and pull down.
With the bag pulled all the way down take the bread knife and slide it along the bottom of the bag to seperate the roots from the bag bottom. Again use the non blade side of the knife as the leading edge.
Good idea