after install, remove partitons and format usb pen drive

I'm having problems removing the partitions so i can reformat my usb pen drive after using to install ubuntu. Is there some sort of how to that anyone can point me to. I can not seem to find one.

using "Disks" I get this output when i try to delete the partitions

Error deleting partition /dev/sdb2: Command-line `parted --script "/dev/sdb" "rm 2"' exited with non-zero exit status 1: Waing: /dev/sdb contains GPT signatures, indicating that it has a GPT table. However, it does not have a valid fake msdos partition table, as it should. Perhaps it was corrupted -- possibly by a program that doesn't understand GPT partition tables. Or perhaps you deleted the GPT table, and are now using an msdos partition table. Is this a GPT partition table?
Error: Both the primary and backup GPT tables are corrupt. Try making a fresh table, and using Parted's rescue feature to recover partitions.
(udisks-error-quark, 0)

under gparted i get this error
/dev/sdb contains GPT signatures, indicating that it has a GPT table. However, it does not have a valid fake msdos partition table, as it should. Perhaps it was corrupted -- possibly by a program that doesn't understand GPT partition tables. Or perhaps you deleted the GPT table, and are now using an msdos partition table. Is this a GPT partition table?

thank you