Composting worms will only grow/populate when they have enough room in their environment, generally.
Cutting back on food or letting them multiply as much as possible to fit their surroundings is up to you. Eventually they'll stop multiplying when they become too numerous.
However, You can keep harvesting them and...
1. Give them away to other budding worm farmers, fishers, etc.
2. Let them go in your garden BUT if you want them to have a fighting chance through the winter then you'll need to provide them with plenty of leaves, shredded paper products, etc.
3. Put them in your outside compost pile if you have one. Many people, such as myself, have compost piles outside as well as inside.
4. Remember, you can always just let them grow to their own liking (in numbers) within the worm bin. Nature will take care of itself. :)
Thanks for the question and hope this sparks some ideas,
~Pauly