CMakeLists folder is not getting ignored with .gitignore

My code structure is as follows

cpppen | |-c++11-features | | | |-async_task | | - async_task.cpp | - CMakeFiles/ | - CMakeLists.txt

I want to add the CMakeFiles/ folder to .gitignore

For some reason it doesn't seem to work.

*.o
*.cbp
*.cmake
CMakeCache.txt
cmake_install.cmake
bin/
build/
CMakeLists.txt.user
**/CMakeFiles/
venv
**/.idea
CMakeScripts
Testing
Makefile

install_manifest.txt
compile_commands.json
CTestTestfile.cmake

cmake-build-debug/

c++11-features/async_task/async_task.exe