Can you post a picture of it so we can see what it looks like?
It the creases are like big pleats, then they probably "won't quilt out" - although I have seen some longarmers pull off some magic.
If you are willing to sacrifice the batting, you might try pulling off what you can, moistening the parts that are still sticking and then pull that batting off.
If you have already washed the backing fabric before you cut it, no need to worry about additional shrinkage.
If you did not wash it before cutting it, I think you might want to make sure it all got wet so it would shrink evenly.
A concern for me about putting it in a washing machine - might all that loose batting clog somethng in the washing machine or drains?
Maybe soak it in a bathtub or very large basin, so you can capture anything loose before it gets in the drain?