reminders: we need to use a mac unit for formatting and a windows unit for testing
here is the step:
step 1. Plug your flashdrive to your mac unit. Wait until it will boot to desktop
step 2. In your mac desktop, go to search/spotlight and type disk utility
step 3. In the disk utility, on the left side portion, select the flash drive you want to make a partition.
step 4. On the right side portion, click the "partition" tab. Then on partition layout, scroll down to "2 partions".
step.5 click on the first partition, write the name and the format to "MS-DOS(FAT). Make sure it is the windows partition first then followed by mac partition
step 6. Click on option, then choose "master boot record" for the windows partition then click ok
step 7. Click on the next partition, write the name and set the format to "Mac OS Extended (Journaled)"
step 8. Click options then click GUID Partition table then click ok.
step 9. click on apply then a pop-up window appear, click on "partition".
wait for the process to finish...
step 10. Unplug the flash drive then plug it to the windows unit. A pop-up window will appear asking you if you would like to format the flash drive. click "format disk".
step 11. Start formatting
step 12. After formatting, unplug your flash drive then plug it back to your mac unit. Go to disk utility then you will see the three partitions, the one on top is the new partition from the windows you just formatted.
step 13. Go to "partition" tab then click on the new partition which is on the upper most part of the partitions.
step 14. Delete the partition by clicking the "delete" button on your keyboard. A pop-up window will appear, click on "remove".
done! you can now try your newly partitioned flash drive :)