ArcGIS Desktop geoprocessing tools require that Python 2.7.18 and Numerical Python 1.9.3. If the ArcGIS Desktop setup does not find either Python 2.7.18 or Numerical Python 1.9.3 (NumPy) installed on the target computer, Python and all required components will be installed . You can choose a Custom installation to unselect the Python feature and avoid installing it. Additionally, if Python is installed during the ArcGIS Desktop installation, you will be provided with the opportunity to choose its installation location. The Python installation location should not include spaces.
Uninstalling Python
When Python, NumPy, and their components are installed by the ArcGIS Desktop setup, they are also uninstalled when you remove ArcGIS Desktop. Although Esri highly recommends that you allow the ArcGIS Desktop setup to install Python, you can install Python 2.7.18, NumPy 1.9.3, and matplotlib and the other resources yourself prior to installing ArcGIS Desktop. If the correct versions of both Python and NumPy are found by the ArcGIS Desktop setup program, Python components will not be installed and, as a result, will not be uninstalled.