Permissions for resource types

I found this at: opencms-forum.de

How to disable the resource type item (explorertype) from showing up (or being chosen) in the explorer

You have to modify the file opencms-modules.xml, add your content type (in this case Author), then remove the permissions (changing GROUP.Users permissions to -r-v-w-c.

<explorertype name="Author" key="fileicon.Author" icon="xmlcontent.gif" reference="xmlcontent">
  <newresource page="structurecontent" uri="newresource_xmlcontent.jsp?newresourcetype=Author" order="225" autosetnavigation="false" autosettitle="false"/>
  <accesscontrol>
    <accessentry principal="GROUP.Administrators" permissions="-r-v-w-c"/>
    <accessentry principal="GROUP.Projectmanagers" permissions="-r-v-w-c"/>
    <accessentry principal="GROUP.Users" permissions="-r-v-w-c"/>                                          
  </accesscontrol>
  <editoptions>
    <defaultproperties enabled="false" shownavigation="false"/>
    <contextmenu/>
  </editoptions>
</explorertype>

or use the default behaviour

<accesscontrol>
  <accessentry principal="DEFAULT" permissions="-r-v-w-c"/>
</accesscontrol>