In order to Safely eject a drive in a macOS environment, perform the following;
1. First, lock the encrypted partition by clicking Lock in the drive's Control Panel.
The following screen will be presented:
2. Locate and click the Unlocker label in the title bar and select Quit Unlocker.
The Private Drive (Secured Volume) will disappear from the Desktop and only leave the Unlocker Volume
3. Click and drag the Unlocker volume to the Trash Can located in the bottom right hand corner of the Desktop.
Once the Unlocker drive disappears from the Desktop, you can physically disconnect the drive from macOS.