--- a/src/pyams_content/shared/site/manager.py	Tue Nov 28 17:26:34 2017 +0100
+++ b/src/pyams_content/shared/site/manager.py	Tue Nov 28 17:27:24 2017 +0100
@@ -61,6 +61,12 @@
     sequence_name = ''  # use default sequence generator
     sequence_prefix = ''
 
+    def is_deletable(self):
+        for element in self.values():
+            if not element.is_deletable():
+                return False
+        return True
+
 
 @subscriber(IObjectAddedEvent, context_selector=ISiteManager)
 def handle_added_site_manager(event):