i did that, it was just stuck in there lol, i made a slit in the cup opened it up that was only way i could have taken it down, i did not know how much water i needed, so i put a lot of it in thereI squeeze the cup a few times, flip it upside down and give it a few taps on the bottom, then while supporting the soil and plant pull it out of the cup and into the new container and backfill with soil. If you have extra of the containers that you are transplanting from what I like to do is place the soil around it then the hole should be the perfect size for your transplant. Make sure you give it a good drink. Good luck!
As long as you didn't leave half the root ball in there you should be fine.i did that, it was just stuck in there lol, i made a slit in the cup opened it up that was only way i could have taken it down, i did not know how much water i needed, so i put a lot of it in there