Restricted Export Formats

You'll need to update your config file on the report server. Once you open the file in Notepad you can remove any extensions you don't want your users to export. Search for the "Render" section. Make sure you take a backup before making any changes.

		<Render>
			<Extension Name="WORDOPENXML"
			           Type="Microsoft.ReportingServices.Rendering.WordRenderer.WordOpenXmlRenderer.WordOpenXmlDocumentRenderer,Microsoft.ReportingServices.WordRendering"/>
			<Extension Name="WORD"
			           Type="Microsoft.ReportingServices.Rendering.WordRenderer.WordDocumentRenderer,Microsoft.ReportingServices.WordRendering"
			           Visible="false"/>
			<Extension Name="EXCELOPENXML"
			           Type="Microsoft.ReportingServices.Rendering.ExcelOpenXmlRenderer.ExcelOpenXmlRenderer,Microsoft.ReportingServices.ExcelRendering"/>
			<Extension Name="EXCEL"
			           Type="Microsoft.ReportingServices.Rendering.ExcelRenderer.ExcelRenderer,Microsoft.ReportingServices.ExcelRendering"
			           Visible="false"/>
			<Extension Name="PPTX"
			           Type="Microsoft.ReportingServices.Rendering.PowerPointRendering.PptxRenderingExtension,Microsoft.ReportingServices.PowerPointRendering"/>
			<Extension Name="PDF"
			           Type="Microsoft.ReportingServices.Rendering.ImageRenderer.PDFRenderer,Microsoft.ReportingServices.ImageRendering"/>
			<Extension Name="IMAGE"
			           Type="Microsoft.ReportingServices.Rendering.ImageRenderer.ImageRenderer,Microsoft.ReportingServices.ImageRendering"/>
			<Extension Name="MHTML"
			           Type="Microsoft.ReportingServices.Rendering.HtmlRenderer.MHtmlRenderingExtension,Microsoft.ReportingServices.HtmlRendering">
				<Configuration>
					<DeviceInfo>
						<DataVisualizationFitSizing>Approximate</DataVisualizationFitSizing>
					</DeviceInfo>
				</Configuration>
			</Extension>
			<Extension Name="CSV"
			           Type="Microsoft.ReportingServices.Rendering.DataRenderer.CsvReport,Microsoft.ReportingServices.DataRendering"/>
			<Extension Name="XML"
			           Type="Microsoft.ReportingServices.Rendering.DataRenderer.XmlDataReport,Microsoft.ReportingServices.DataRendering"/>
			<Extension Name="ATOM"
			           Type="Microsoft.ReportingServices.Rendering.DataRenderer.AtomDataReport,Microsoft.ReportingServices.DataRendering"/>
			<Extension Name="NULL"
			           Type="Microsoft.ReportingServices.Rendering.NullRenderer.NullReport,Microsoft.ReportingServices.NullRendering"
			           Visible="false"/>
			<Extension Name="RGDI"
			           Type="Microsoft.ReportingServices.Rendering.ImageRenderer.RGDIRenderer,Microsoft.ReportingServices.ImageRendering"
			           Visible="false"/>
			<Extension Name="HTML4.0"
			           Type="Microsoft.ReportingServices.Rendering.HtmlRenderer.Html40RenderingExtension,Microsoft.ReportingServices.HtmlRendering"
			           Visible="false">
				<Configuration>
					<DeviceInfo>
						<DataVisualizationFitSizing>Approximate</DataVisualizationFitSizing>
					</DeviceInfo>
				</Configuration>
			</Extension>
			<Extension Name="HTML5"
			           Type="Microsoft.ReportingServices.Rendering.HtmlRenderer.Html5RenderingExtension,Microsoft.ReportingServices.HtmlRendering"
			           Visible="false">
				<Configuration>
					<DeviceInfo>
						<DataVisualizationFitSizing>Approximate</DataVisualizationFitSizing>
					</DeviceInfo>
				</Configuration>
			</Extension>
			<Extension Name="RPL"
			           Type="Microsoft.ReportingServices.Rendering.RPLRendering.RPLRenderer,Microsoft.ReportingServices.RPLRendering"
			           Visible="false"
			           LogAllExecutionRequests="false"/>
		</Render>

This was such a simple problem. The answer was using the PBI visualization Visual>Export settings.