How to get main drain off

Hello,
My pool is completely empty right now as we have been going through a major clean up. I cannot figure out how to get the main drain lid off at the bottom of pool to clean out all the leaves and debris that has clogged it. I wish I could attach a picture of it but it is a round piece of plastic with two small holes on either side but appears to have no screws in it. If anyone can help me attach a photo from my phone to this post it would be greatly appreciated.
Thank you.
Emily