How do you delete partitions on a USB Flash Drive?

I recently used an 8gb sandisk flash drive to try out the newest version of Hexxeh's Flow build of chromium os. As part of the process I had to write an img file to my flash drive that was about 1.6gb large. However, now I want to have my normal flash drive back but the thing is partitioned weirdly because of the image. I've figured out that I have 3 separate partitions on my flash drive. 1 is 256mb one is 1.6gb and the rest is just unused storage space. I want to delete the other partitions and just have on 8gb partition on my flash drive. However, windows vista doesn't let you have more than 1 partition of a flash drive and it only sees the 256mb one. It also won't let me delete the partitions off the flash drive. If anyone knows a free way to get rid of partitions on a flash drive please let me know.