[Steven Zahm]

@ Lan

Are you suing categories at all? I ask, because there are only really two methods to hide/remove that field and one will remove any assigned categories upon edit.

To hide the “Visibility” option can only be done with CSS. Add the following to the end of the cn-admin.css file:

.postbox .visibility {
    display: none;
}

Adding the following CSS will hide the category metabox:

#categorydiv {
    display: none;
}

Hope that helps.