The following tutorial will show you how to encrypt a USB or external drive on your Mac.
The Service Desk cannot retrieve passwords for you. If you lose the bitlocker password, your information is lost.
As a note, remember that all the data on the drive you will be encrypting will be erased. So, if you have anything important on your thumb drive, you should transfer it in a safe location on your Desktop until the drive is encrypted.
To begin the encryption process, open Disk Utility (located in /Applications/Utilities). You can also search for the Disk Utility in your spotlight search.
Once there, click on your thumb drive name in the sidebar, and then click on the Erase tab. From the Format drop-down menu, select "Mac OS X Extended (Journaled, Encrypted)." You can rename your USB if you so choose.
After doing this, a window will appear, requesting that you enter a new password, and then verify it. For recovery purposes, you will be able to enter a password hint. When finished, click on the Erase button again.
You will be able to see how secure your password is during this process.
Disk Utility will then begin the Erase and Encryption process. The amount of time that it will take to complete the process will depend on the size of the drive. After the drive format has finished, you may close Disk Utility.