I did this
I had a sub domain I wanted on its own account.
using SSH I just did
mv /home/firstcpanelname/public_html/folder /home/secondcpanelname/public_html
Then permissions and ownership needed to be fixed so I did
chown -R secondcpanelname:secondcpanelname /home/secondcpanelname
chmod -R 0755 /home/secondcpanelname
To change all permissions over and set all files to 755 so su_php wouid work ok still.
I still had the files in a folder though under the second account, but that was a few seconds with transmit and moving them to the parent folder.
The -R on the chown and chmod does it recursively, so it does it for all folders and files below your cpanelname directory.
As a note. you can use cp instead of mv to copy the files instead of moving them if you wish to have a copy for a bit.