All,
Should you wish to recreate your Docker virtual disk image from scratch, but retain your application data to avoid requiring reconfiguration for certain apps, the process is simple.
Step 1: Delete your previous image file
Login to your system from the unRAID webGui (http://tower or http://tower.local from Mac by default).
Navigate to the Docker tab.
Stop the Docker service if it is not already.
Click the checkbox next to the Docker image