How to hide an accordion in a accordion menu?

Hi team,

i have this accordion panel named menuPanel:

<accordionPanel multiExpand="Y" resizable="Y">
  <accordion name="menu1" panelName="menuPanel1" order="10" title="title 1"/>
  <accordion name="menu2" panelName="menuPanel2" order="20" title="title 2"/>
  <accordion name="menu3" panelName="menuPanel3" order="30" title="title 3"/>
  <accordion name="menu4" panelName="menuPanel4" order="40" title="title 4"/>
</accordionPanel>

I want to hide accordion menu4 for specific users and think i must do it by calling:

api_accordionpanel.removeAccordion('menuPanel','menu4');

When i add this line to the application post-open event, nothing happens, that is, menu 4 is still shown. When i run the form in debug mode, formspider throws this error message:

ERROR :  BDF_ResponseDispatcher.executeActions RemoveAccordion Cannot read property 'appendTo' of null undefined

I thought perhaps the timing is not right, so i removed it from the post-open event and moved it to the postinitialize event of the accordion itself. The error however remains the same.

How can i hide accordion menu4 ?

Kind regards, Jan Willem Vermeer