Last night I used Boot Camp to install Windows 10 on my 2014 Macbook Pro 13". All went smoothly with the installation, but I ran into an issue when I went to format the USB drive I used for the setup. (Formatted as FAT32) I couldn't format it with Disk Utility because it was found to be read only. So I popped into terminal and tried to format it with "diskutil" using superuser permissions. Still wouldn't work. I was getting Error code 69877. So I attempted to use the gpt tool to force delete the partition, but it was telling me "Permission Denied." I booted to Windows to try erasing it there. I tried all the methods I know including formatting it through Windows Explorer, Administrator Tools, and diskpart in a command prompt. Nothing is working. This drive REALLY doesn't want to be formatted. Any suggestions?