How do I set a command line variable back to its default value?

Same question here. Is there a command to set specific commands-line-commands back to default, so they do not prompt the following anymore:
“Setting the console variable ‘xxx’ with ‘SetByScalability’ was ignored as it is lower priority than the previous ‘SetByConsole’. Value remains ‘X’”

How it is possible to command-line-command back to “default” and “not overwrite with last command line” command anymore?
With “set back to default” I mean, to set the value back to related scalability settings value.