Hi @Brittany B,
I would recommend that you contact support so that they can make sure it is closed out correctly. Just open your AdWords Express account and click on the three dots in the upper right hand corner and click on Help.
Google AdWords Top Contributor | Google Partner | GYBO | Local Guide | My Profile
Re: cancel account
@J Clemens is correct.
Also, in the meantime, make sure you log in to your account and pause or delete your current ad, so that charges will not continue to accrue.
Google AdWords Top Contributor