How to hide attributes in one field via Arcade expression language - ArcGIS Online

The article Russ mentioned above is a nice way to go if you are want to configure a nice look to the Popup. If you're looking for a quick way without much configuration you can go with something like this:

var skipFields = ['Creator', 'CreationDate', 'Editor', 'EditDate', 'OBJECTID', 'GlobalID'];
var allFields = '';
for(var i in $feature){
    var skip = False;
    for(var j in skipFields){
        if(Text(i) == Text(skipFields[j])){
            skip = True;
        }
    }

    if(isEmpty($feature[i])){
        Console(Concatenate('Null Field: ', i));
    } else if (skip){
        Console(Concatenate('Skipping Field: ', i));
    } else {
        Console(Concatenate('Including Field: ', i));
        allFields = Concatenate([allFields, Upper(i), TextFormatting.NewLine, Text($feature[i]), TextFormatting.NewLine, TextFormatting.NewLine]);
    }
}

Console(allFields);
return allFields;

It returns a basic output as below:

Quick but a little raw!