I got a partition that is probably created by dd, and is about 200MB on a 4GB USB stick. I am failing to delete it using GParted (the option is greyed on the right-click menu).
Open a terminal
so sudo fdisk /dev/sdb
then press d
to delete the partition if its the only one there it will auto select otherwise it will prompt for partition number
then press w to write the changes to the disk
Try unmounting it from commandline:
If you cannot delete it in any way, create a similar partition in a loopback device and
Then, you must install the programs to create a FAT32 partition again.
I think the reason the option was greyed out is because the stick wasn't actually unmounted. It's a bug in GParted because I unmounted it using its Unmount right-click menu option, and I didn't get a message saying the operation failed.