Fix cache delete

service/admin.py

@@ -45,6 +45,10 @@ class CategoryAdmin(admin.ModelAdmin):
         obj.save()
         cache.clear()
 
+    def delete_model(self, request, obj):
+        obj.delete()
+        cache.clear()
+
 
 class GroupAdmin(admin.ModelAdmin):
     list_display = ('name', 'category', 'visible')
@@ -53,6 +57,10 @@ class GroupAdmin(admin.ModelAdmin):
         obj.save()
         cache.clear()
 
+    def delete_model(self, request, obj):
+        obj.delete()
+        cache.clear()
+
 
 class PlacementPointAdmin(admin.ModelAdmin):
     pass