The showLoadingLabel property (boolean) determines whether the loading label will be displayed while the bubble is waiting for the content to load.
The bubble is waiting for content if onLoad uses asynchronous mode or when the content is loaded using the server-side Load event (ASP.NET WebForms, ASP.NET MVC, Java versions).
true
var bubble = new DayPilot.Bubble({
showLoadingLabel: false,
// ...
});