Hello Mike,

Thank you for posting in our community.

By design the buttonType option of the filtering editor is set to "clearButton" when the editor is initialized. Since this option can not be set runtime the only suggestion that I can make is hiding this button once it is rendered. This can be achieved in the dataFiltering event. For example:

              features: [
                    {
                        name: "Filtering",
                        mode: "simple",
                        filterDialogContainment: "window",
						dataFiltering: function (evt, ui) { 
							$(".ui-igedit-cleararea").hide() 
						 }
                    },

Please keep in mind that with this approach the button will be shown and afterwards hidden.

From version 18.2 on, we will provide the user with the ability to set filtering editorOptions, as we currently provide this for Updating editorOptions. 

Please let me know if you need any further assistance with this matter.