remove file extension in a folder.

Your description is unclear.

If you want to rename the files on your hard drive, make a backup of your folder and then use this code:

var myFiles = (new Folder("C:/Documents and Settings/Variables/Desktop/XYZ")).getFiles();
for (var i = 0; i < myFiles.length; i++) {
    var myFile = myFiles;
    if (myFile instanceof File) {
        var myFileName = myFile.displayName;
        myFile.rename(myFileName.slice(0, myFileName.lastIndexOf(".")));
    }
}

If you want an array of file names without extensions, use this code:

myFolder = new Folder("C:/Documents and Settings/Variables/Desktop/XYZ");
var myFiles = myFolder.getFiles(function(file) {return myFile instanceof File;});
for (var i = 0; i < myFiles.length; i++) {
    var myFileName = myFiles.displayName;
    myFiles = myFileName.slice(0, myFileName.lastIndexOf("."));
}
alert(myFiles.toString());