diff --git a/api-guide/source/conf.py b/api-guide/source/conf.py
index dca789527..e77849a35 100644
--- a/api-guide/source/conf.py
+++ b/api-guide/source/conf.py
@@ -1,5 +1,3 @@
-# -*- coding: utf-8 -*-
-
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
 # You may obtain a copy of the License at
diff --git a/doc/source/conf.py b/doc/source/conf.py
index aac598941..2326a770b 100644
--- a/doc/source/conf.py
+++ b/doc/source/conf.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
 # You may obtain a copy of the License at
diff --git a/releasenotes/source/conf.py b/releasenotes/source/conf.py
index 020e8b4bf..3eeb27051 100644
--- a/releasenotes/source/conf.py
+++ b/releasenotes/source/conf.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
 # You may obtain a copy of the License at