windows - pip upgradeするとうまくいかない

python -mならうまくいくみたい

> python -m pip install --upgrade pip
Collecting pip
  Using cached pip-21.0-py3-none-any.whl (1.5 MB)
Installing collected packages: pip
  Attempting uninstall: pip
    Found existing installation: pip 20.1.1

=>

うまくいかない場合

> pip install --upgrade pip      
Collecting pip
  Using cached pip-21.0-py3-none-any.whl (1.5 MB)
Installing collected packages: pip
  Attempting uninstall: pip
    Found existing installation: pip 20.1.1
    Uninstalling pip-20.1.1:
Consider using the `--user` option or check the permissions.

file : pip.conf

[global]
user=false

をやったが駄目だった。