@Execute
  public void execute(final MApplication application, final EModelService service, final Display display)
  {
    final IEclipseContext context = application.getContext();

    //here, the correct menuContribution is found
    final List<MMenuContribution> collect =
      application.getMenuContributions().stream()
        .filter(menuContribution -> menuContribution.getElementId().equals("ui.menucontribution.help"))
        .collect(Collectors.toList());
    for (final MMenuContribution menu : collect)
    {
     //the following 3 lines are executed, but have no effect
      application.getMenuContributions().remove(menu.getElementId());
      menu.setToBeRendered(false);
      menu.setVisible(false);
    }

    application.getMenuContributions().clear();
  }

void removeCommand(String commandId, MApplication application) {
	for (MCommand command : application.getCommands().toArray(new MCommand[application.getCommands().size()])) {
		if (commandId.equals(command.getElementId())) {
			Collection<Setting> collection = EcoreUtil.UsageCrossReferencer.find((EObject) command, (EObject) application);
			for (Setting setting : collection) {
				if (setting.getEObject() instanceof MUIElement) {
					MUIElement uiElement = (MUIElement)setting.getEObject();
					uiElement.setToBeRendered(false);
				} 
			}
		}
	}
}

@Execute
public void execute(final MApplication application, final EModelService service, final Display display) {
 <logic associated to the menuItem>
}

@CanExecute
public boolean canExecute(MMenuItem menuItem) {
   menuItem.setVisible(false);
   return false;
}