diff --git a/doc/source/api/csst_proto.rst b/doc/source/api/csst_proto.rst
index cdfced7bf2b224830748a1fa3c6d0063270c4767..c48cffe04116f8f73c18fb402cc2cfc8370f76d4 100644
--- a/doc/source/api/csst_proto.rst
+++ b/doc/source/api/csst_proto.rst
@@ -1,6 +1,9 @@
 API
 ===
 
+In this chapter, we show what the rendered Numpy-style docstring looks like
+in sphinx documentation.
+
 .. automodule:: csst_proto.top_level_interface
    :noindex:
    :members:
diff --git a/doc/source/git.rst b/doc/source/git.rst
deleted file mode 100644
index 2abb952ddae7c87cc6346346b61ac15d6a81d669..0000000000000000000000000000000000000000
--- a/doc/source/git.rst
+++ /dev/null
@@ -1,32 +0,0 @@
-Version Control
-===============
-
-A functional quality software needs a version control system,
-which provides several advantages.
-
-    1. Record versions
-        so that you can rollback the software to any history version.
-    2. Collaboration between developers
-        so that multiple developers can work simultaneously to enhance efficiency.
-    3. Keep multiple braches
-        so that software can be developed in a separate branch
-        and it does not affect the stable (released) version.
-    4. Code safety
-        the approve-merge mechanism, etc.
-
-`git`
------
-`git` is probably the most widely used version control system presently.
-
-    - official website: https://git-scm.com/
-    - **Pro Git** (2nd Ed.): https://git-scm.com/book/en/v2
-
-CSST DAS GitLab
----------------
-CSST DAS uses a self-managed `gitlab` instance to host data processing pipelines at
-
-- https://csst-tb.bao.ac.cn/code
-
-The Level 1 pipeline is host in `csst-l1` group:
-
-- https://csst-tb.bao.ac.cn/code/csst-l1
diff --git a/doc/source/sphinxdoc.rst b/doc/source/sphinxdoc.rst
deleted file mode 100644
index fe05b9885e5c655a5b53303585a596470fe97e7e..0000000000000000000000000000000000000000
--- a/doc/source/sphinxdoc.rst
+++ /dev/null
@@ -1,8 +0,0 @@
-Sphinx-based documentation
-==========================
-
-The sphinx homepage:
-    - https://www.sphinx-doc.org/en/master/index.html
-
-A tutorial on how to write restructured text (.rst) files:
-    - https://docutils.sourceforge.io/rst.html