Why would you want to flip the removable bit on your USB Drive?
Which USB Drive do you have?
If you want to partition your USB Flash Drive then you can use Bootice
If you really want to flip the removable bit then you have use Mass Production tools to reprogram the microcontroller in your USB Flash Drive. However this procedure varies for all USB Flash Drives. Most Mass Production tools are used to repair USB Flash Drives or to add or remove CDFS Partition; However, some MP Tools provide the option to Flip the Removable bit.
The general procedure to reprogram your USB Flash Drive to Flip the bit or make other changes is as follows:
Download and Run Chipgenius and find out the VID and PID of your USB Drive.
Go to http://flashboot.ru/iflash.html and enter the VID and PID of your USB Drive.Check if there are any MassProduction tools available and download them. Then you will have to figure how to use it.
Check this for detailed guide on how to do this.(In this guide the MPtool is being used to repair a fake USB Drive)
Warning - The procedure varies for different USB Flash Drives and you may end up with irreparable USB Flash Drive.
I have tried flipping the bit of Transcend Jetflash USB Drives with good success. The MPtool for JetFlash USB Drives is called AlcorMptool and this MpTool has the option to flip the removable bit.
Another reason why I feel comfortable to use JetFlash USB Drives is because it can be fixed easily if something goes wrong.