Remove "delete from diagram" context menu action

plugins/org.yakindu.sct.ui.editor/plugin.xml

@@ -215,6 +215,10 @@
             <popupStructuredContributionCriteria objectClass="org.yakindu.sct.ui.editor.editparts.StatechartTextExpressionEditPart"/>
             <popupPredefinedItem id="editGroup" remove="true"/>
          </popupContribution>
+         <popupContribution class="org.eclipse.gmf.runtime.diagram.ui.providers.DiagramContextMenuProvider">
+			<popupStructuredContributionCriteria objectClass="org.eclipse.gmf.runtime.diagram.ui.editparts.IGraphicalEditPart"/>
+			<popupPredefinedItem id="deleteFromDiagramAction" remove="true"/>
+		</popupContribution>
       </contributionItemProvider>
    </extension>