diff --git a/Optimization.md b/Optimization.md
index 23568c1..ccc4aa5 100644
--- a/Optimization.md
+++ b/Optimization.md
@@ -127,7 +127,7 @@ will also generate a "pictures" collection and a "documents" collection if they
 
 Actually, the actual data files have the collection name as the prefix, e.g., "pictures_1.dat", "documents_3.dat".
 
-In case you need to delete them later, you can go to the volume servers and delete the data files directly, for now. Later maybe a deleteCollection command may be implemented, if someone asks...
+If you need to delete them later see https://github.com/chrislusf/seaweedfs/wiki/Master-Server-API#delete-collection
 
 ## Logging