It all started when I was attempting to format my PNY USB drive because it was full of junk. When it asked me what type of file system, I selected FAT but there was a checkbox below that said "Encrypt" and I accidently checked it and continue.

I had no choice but to come up with a passphrase for it, and so I did, thinking I was able to remove that encryption. But after that at Disk Utility I thought I would find a "Remove Encryption" button or something like that but I didn't.

I tried formatting it to remove the encryption but it gives me an error:

Error Formatting, The device is busy"
Detail>>> One or more block devices are holding /dev/sdb/.

I am stuck, what should I do?