Re: Remove all character styles unless in group 'X'

try this...

var myDoc = app.activeDocument;

var myStyleGroup = myDoc.characterStyleGroups

for (var i = myStyleGroup.length-1;i>=0;i--){

    alert (myStyleGroup[i].name)

    if (myStyleGroup[i].name!='X'){

        myStyleGroup[i].remove()

        }

    }