Is it possible to hide or remove the Powered by Esri attribution on custom web applications?

Answer

It is not possible to hide or remove the Powered by Esri attribution on custom web applications. Esri requires users to include the Esri attribution when using Esri items to build and deploy applications, for example, basemap layers from the basemap layer service, data layers, Esri API and SDK technology, or other Esri data services. This requirement includes attribution from other non-Esri sources. Refer to ArcGIS Developer: Attribution for more information.