Following works with Windchill 10.2 M10
private boolean removePrimaryContent(final WTDocument wtDoc) {
boolean isSuccess = false;
ContentItem contentItem = null;
try {
contentItem = ContentHelper.service.getPrimary((FormatContentHolder)wtDoc);
if(contentItem != null){
System.out.println("deleting contentItem: " + contentItem.getDisplayIdentity());
PersistenceHelper.manager.delete(contentItem);
isSuccess = true;
}
} catch (WTException | PropertyVetoException e) {
isSuccess = false;
e.printStackTrace();
}
return isSuccess;
}