How to remove password security measure?

Hello, I need to restore my Mac with Time Machine. I have my Time Machine Back up on my WD external drive. The problem is that the system to restore the content from the drive is not able to identify the drive because it is encrypted with a password (this is what we figured out with the Apple assistant). My question is then: how to remove the password security measure from the disk? My fear is to loose all the content of the drive by reformatting it.
(I do have the password).
Your help will be greatly appreciated!
Thanks!

If you’d encrypted the drive using WD Security, then you can reinstall WD Security to remove password from the drive.