Regarding the permissions command, try using sudo in front of your terminal command:
sudo pip install --upgrade pip
Sudo allows you to run the command with the privileges of the superuser and will install the package for the global, system-wide Python installation. Ideally, you should create a virtual environment for the project you are working on. Have a look at this
Regarding the python Try running pip as an executable like this:
python3.6 -m pip install <package>