You didn't do anything wrong. The leaves will die naturally and you need to let them. Like daffodils, wait until the leaves are brown and dead looking before you cut them off. Like @cyndi said, they need those leaves to photosynthesis the sun's energy into the bulb so the bulb can make it thru the winter.
You can also click the name of the plant to get to the encyclopedia. It's an amazing app full of wonderful people. I hope you enjoy it. If you want someone to see your post or your comment put the ampersand before the name and it will come to their attention. Like I did with Cyndi @cyndi Now she will see it and she is a sweetheart and won't care. Enjoy!