Well, as your topic header suggests, just undeploy them again (using the same button / hot key that you used to deploy them). After they have undeployed themselves (takes abot 5 secs.) you are free to move them and redeploy them at your discrection.
A quick way to do a few at once is to double click on any of the artillery units, which will select ALL the artillery currently under your command. You can then deploy / undeploy then en masse.
I hope this is what you wanted to know!
"Life. Don't talk to me about life." (Marvin the paranoid android).