To encrypt a USB memory stick or an external hard drive, follow these steps:
In the search bar on the taskbar, type bitlocker.
A list of search results appears.
Click Manage BitLocker.
The BitLocker Drive Encryption window appears.
In the BitLocker Drive Encryption window, find the removable drive that you want to encrypt and click it.
A list with options appears.
Click the Turn on BitLocker button for that drive.
Turning on BitLocker for a removable drive.You’re asked to choose how you want to unlock this drive.
Select Use a Password to Unlock the Drive.
The fields for entering the password and confirming it now are editable.
Type the password in the appropriate fields; then click Next.
How you want to unlock the removable drive.You’re asked where you want to back up your recovery key.
Click the option you prefer; then click Next.
You’re asked to choose how much of your drive you want to encrypt and given two options: encrypt the used disk space only or encrypt the entire drive.
Choose how much of your drive you want to encrypt and click Next.
You’re asked whether you’re ready to encrypt the selected drive.
Click Start Encrypting.
When the encryption is done, click Close.