clear old axis titles on cartesian clean

Author: etpinard

src/plots/cartesian/index.js

@@ -166,9 +166,14 @@ exports.clean = function(newFullData, newFullLayout, oldFullData, oldFullLayout)
 
     if(hadCartesian && !hasCartesian) {
         var subplotLayers = oldFullLayout._cartesianlayer.selectAll('.subplot');
+        var axIds = Axes.listIds({ _fullLayout: oldFullLayout });
 
         subplotLayers.call(purgeSubplotLayers, oldFullLayout);
         oldFullLayout._defs.selectAll('.axesclip').remove();
+
+        for(i = 0; i < axIds.length; i++) {
+            oldFullLayout._infolayer.select('.' + axIds[i] + 'title').remove();
+        }
     }
 };