diff --git a/bx_py_utils/doc_write/README.md b/bx_py_utils/doc_write/README.md
index 6e28af8..c2ef25e 100644
--- a/bx_py_utils/doc_write/README.md
+++ b/bx_py_utils/doc_write/README.md
@@ -47,7 +47,9 @@ Add a section `[tool.doc_write]` to your `pyproject.toml` to configure Doc-Write
 docstring_prefix = 'DocWrite:'
 output_base_path = './docs/'
 search_paths = ['./foo/', './bar/']
+delete_obsolete_files = false  # Delete obsolete files in output_base_path
 ```
+Warning: Turn `delete_obsolete_files` only on if output_base_path is excursively used by Doc-Write.
 
 ### Howto
 
@@ -68,6 +70,9 @@ Notes:
 
 * The created created Markdown file is relative to `output_base_path` (defined in `pyproject.toml`)
 
+* If `delete_obsolete_files` is set to `true` in `pyproject.toml`,
+  then all `*.md` files in `output_base_path` that are not in `doc_paths` will be deleted.
+
 * Headlines will be sorted, so they appears ordered by the level.
 
 * All Doc-String without the `{prefix}` will be ignored.
diff --git a/bx_py_utils/doc_write/api.py b/bx_py_utils/doc_write/api.py
index ffb784f..48b2329 100644
--- a/bx_py_utils/doc_write/api.py
+++ b/bx_py_utils/doc_write/api.py
@@ -37,6 +37,8 @@ class FooBar:
 def generate(base_path: Path | None = None) -> list[Path]:
     config: DocuwriteConfig = get_docu_write_cfg(base_path=base_path)
 
+    output_base_path: Path = config.output_base_path
+
     doc_paths = []
     docs_data = collect_docstrings(config=config)
     for rel_file_path, data in sorted(docs_data.items()):
@@ -49,12 +51,25 @@ def generate(base_path: Path | None = None) -> list[Path]:
             docs.append('\n\n'.join(docstrings))
         merged_doc = '\n\n'.join(docs)
 
-        """ DocWrite: bx_py_utils/doc_write/README.md ### Notes
+        """DocWrite: bx_py_utils/doc_write/README.md ### Notes
         * The created created Markdown file is relative to `output_base_path` (defined in `pyproject.toml`)
         """
-        out_path = config.output_base_path / rel_file_path
+        out_path = output_base_path / rel_file_path
         logger.info('Write %s', out_path)
         out_path.parent.mkdir(parents=True, exist_ok=True)
         out_path.write_text(merged_doc, encoding='UTF-8')
         doc_paths.append(out_path)
+
+    if config.delete_obsolete_files:
+        """DocWrite: bx_py_utils/doc_write/README.md ### Notes
+        * If `delete_obsolete_files` is set to `true` in `pyproject.toml`,
+          then all `*.md` files in `output_base_path` that are not in `doc_paths` will be deleted.
+        """
+        current_files = set(doc_paths)
+        existing_files = set(output_base_path.rglob('**/*.md'))
+        obsolete_files = existing_files - current_files
+        for obsolete_file in obsolete_files:
+            logger.info('Delete %s', obsolete_files)
+            obsolete_file.unlink()
+
     return doc_paths
diff --git a/bx_py_utils/doc_write/cfg.py b/bx_py_utils/doc_write/cfg.py
index 7e38a0f..550fbf8 100644
--- a/bx_py_utils/doc_write/cfg.py
+++ b/bx_py_utils/doc_write/cfg.py
@@ -24,13 +24,16 @@ class DocuwriteConfig:
     docstring_prefix = 'DocWrite:'
     output_base_path = './docs/'
     search_paths = ['./foo/', './bar/']
+    delete_obsolete_files = false  # Delete obsolete files in output_base_path
     ```
+    Warning: Turn `delete_obsolete_files` only on if output_base_path is excursively used by Doc-Write.
     """
 
     base_path: Path
     search_paths: list[Path]
     output_base_path: Path
     docstring_prefix: str = 'DocWrite:'
+    delete_obsolete_files: bool = False  # Delete obsolete files in output_base_path
 
     def __post_init__(self):
         self.base_path = self.base_path.resolve(strict=True)
diff --git a/bx_py_utils_tests/tests/test_doc_write_api.py b/bx_py_utils_tests/tests/test_doc_write_api.py
index 75b91f4..9b4fde3 100644
--- a/bx_py_utils_tests/tests/test_doc_write_api.py
+++ b/bx_py_utils_tests/tests/test_doc_write_api.py
@@ -5,6 +5,7 @@
 
 from bx_py_utils.doc_write.api import generate
 from bx_py_utils.doc_write.cfg import DocuwriteConfig, get_docu_write_cfg
+from bx_py_utils.path import assert_is_file
 
 
 class DocuWriteApiTestCase(TestCase):
@@ -71,11 +72,16 @@ def test_happy_path(self):
                 ),
             )
 
+            # Create an "obsolete" file:
+            obsolete_md_path = temp_path / 'docs/test/obsolete.md'
+            obsolete_md_path.parent.mkdir(parents=True, exist_ok=False)
+            obsolete_md_path.touch()
+
             created_readme_path = temp_path / 'docs/test/README.md'
             self.assertIs(created_readme_path.exists(), False)
             doc_paths = generate(base_path=temp_path)
             self.assertEqual(doc_paths, [created_readme_path])
-            generated_content = created_readme_path.read_text(encoding='UTF-8')
+            generated_content = created_readme_path.read_text()
             self.assertEqual(
                 generated_content,
                 inspect.cleandoc(
@@ -92,3 +98,19 @@ def test_happy_path(self):
                     """
                 ),
             )
+
+            # The default is not to delete obsolete files -> does it still exists?
+            assert_is_file(obsolete_md_path)
+
+            # Activate deleting of obsolete files:
+            with pyproject_toml_path.open('a') as f:
+                f.write('\ndelete_obsolete_files = true\n')
+
+            # Run again and delete obsolete files:
+            generate(base_path=temp_path)
+
+            # Obsolete file removed?
+            self.assertIs(obsolete_md_path.exists(), False)
+
+            # readme is still the same?
+            self.assertEqual(created_readme_path.read_text(), generated_content)
diff --git a/pyproject.toml b/pyproject.toml
index c5793ee..a33c598 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "bx_py_utils"
-version = "90"
+version = "91"
 description = "Various Python utility functions"
 homepage = "https://github.com/boxine/bx_py_utils/"
 authors = [