I doubt that you will catch all of unwanted fish. Some of them will stay...They will breed and probably you will never get rid of them.
The only possible way to get rid of them is to get rid of water! Is there any water regulation system in your pond that allows you to let water flow away? If answer is YES then do it. The next rain will fill your pond again and it will be suitable for bluegill.
You can also use pump to achieve the same goal. It's possible with such 1/4 acre pond.
By the way, can you even imagine, what would you do with so much small fish?
If you are not in hurry, these small fish could be a great food for some predator fish species. But that will delay your bluegill plans for some years of course.
