Encrypt the disk with security for the Paranoid.
This is a terrific replacement/continuance of TrueCrypt and works perfectly on Windows 10. HOWEVER, the authors have stated on their website that they prefer sites like CNET only supply a link, not the actual download. So, don't install this very much older version, but instead search for VeraCrypt's site and download directly. It installs and looks like TrueCrypt. You'll want to update your old TrueCrypt containers, though it has a backward compatibility feature to allow use of them. Note that the newer containers take longer to open now...a symptom of better encryption.