Step 1: Materials
Step 2: Remove the Brim
There should be stitches where the brim is, so the first step is to cut them and take them out. Once you cut one you can usually just pull the stitches out so this part is fairly simple.
With the beanie inside out make a small cut, about 3/4 to 1 inch a couple inches above were the beanie is. Then reach inside the hole and pull of the brim.
Step 3: Remove the Extra Fabric
So your gonna pull the beanie up into a tent, and then pin it at the bottom of the tent of fabric. Then cut off the tent so it looks as if there was no extra fabric, look at the image above if that was confusing.
Then sew it back together.