diff --git a/GPy/core/parameterization/index_operations.py b/GPy/core/parameterization/index_operations.py
index ebfe2904..891ac522 100644
--- a/GPy/core/parameterization/index_operations.py
+++ b/GPy/core/parameterization/index_operations.py
@@ -95,6 +95,9 @@ class ParameterIndexOperations(object):
     def __getitem__(self, prop):
         return self._properties[prop]
 
+    def __delitem__(self, prop):
+        del self._properties[prop]
+
     def __str__(self, *args, **kwargs):
         import pprint
         return pprint.pformat(dict(self._properties))