So you actually can just delete your volume1 (after backing up all of your data of course) and that will allow you to keep all of your DSM configs as you can just create an encrypted volume1 and move everything back to it
The only thing I am not sure of is all the docker stuff I have set up:
Are all the docker images going to have to be re-installed, or will they just come back and work if I restore the old data (onto the same shared folder names) in the new DSM 7.2 install?