I couldn't format/delete my USB flash drive using GParted and it is locked too.
When right click on it, the format and delete options are grayed out.
Please help me.
First unmount the USB, Type in Terminal:
sudo umount /dev/YOUR_USB
YOUR_USB is the Filesystem, to get it Type in Terminal:
umount you should be able to format the USB using GParted.
Here is an example:
$ df /media/bg/120GB/ Filesystem 1K-blocks Used Available Use% Mounted on /dev/sdb1 115247656 22539168 86831140 21% /media/bg/120GB $ sudo umount /dev/sdb1
In addition to Benny's suggestion of how to unmount the partition, you can also unmount from within GParted.
Assuming that you did not boot from the USB drive, you can unmount the USB partition in GParted using the Partition -> Unmount menu option. After the partition is unmounted then you should be able to format it.