How do I get storage back to normal on USB?

[zedthehedgehog]

I have a cheap 64GB HP USB, that I would've used as a live USB.
I installed Linux mint on it.
However, upon running Linux mint using the USB, I forgot to set it to have enough storage for settings, downloads, etc. and I was going to use it as a normal USB now that I fluffed up the installation.
Then, 2nd problem. I didn't take the time to look up how to format it correctly, and now it's stuck at 3MB of storage.
Any help?