pythonでtweepyを使いたいがインストールできない

pythonでtweepyを使いたいのですがpipでインストールしようとしてもエラーが出ます...
sixが原因？かもしれないと思いignore-install sixにしたんですがそれも同じでした。原因がわかりません...

Collecting tweepy
Using cached tweepy-3.5.0-py2.py3-none-any.whl
Requirement already satisfied (use --upgrade to upgrade): requests>=2.4.3 in /Library/Python/2.7/site-packages (from tweepy)
Collecting six>=1.7.3 (from tweepy)
Using cached six-1.10.0-py2.py3-none-any.whl
Requirement already satisfied (use --upgrade to upgrade): requests-oauthlib>=0.4.1 in /Library/Python/2.7/site-packages (from tweepy)
Requirement already satisfied (use --upgrade to upgrade): oauthlib>=0.6.2 in /Library/Python/2.7/site-packages (from requests-oauthlib>=0.4.1->tweepy)
Installing collected packages: six, tweepy
Found existing installation: six 1.4.1
DEPRECATION: Uninstalling a distutils installed project (six) has been deprecated and will be removed in a future version. This is due to the fact that uninstalling a distutils project will only partially uninstall the project.
Uninstalling six-1.4.1:
Exception:
Traceback (most recent call last):
File "/Library/Python/2.7/site-packages/pip-8.0.2-py2.7.egg/pip/basecommand.py", line 209, in main
status = self.run(options, args)
File "/Library/Python/2.7/site-packages/pip-8.0.2-py2.7.egg/pip/commands/install.py", line 317, in run
prefix=options.prefix_path,
File "/Library/Python/2.7/site-packages/pip-8.0.2-py2.7.egg/pip/req/req_set.py", line 725, in install
requirement.uninstall(auto_confirm=True)
File "/Library/Python/2.7/site-packages/pip-8.0.2-py2.7.egg/pip/req/req_install.py", line 752, in uninstall
paths_to_remove.remove(auto_confirm)
File "/Library/Python/2.7/site-packages/pip-8.0.2-py2.7.egg/pip/req/req_uninstall.py", line 115, in remove
renames(path, new_path)
File "/Library/Python/2.7/site-packages/pip-8.0.2-py2.7.egg/pip/utils/init.py", line 266, in renames
shutil.move(old, new)
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/shutil.py", line 303, in move
os.unlink(src)
OSError: [Errno 13] Permission denied: '/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/six-1.4.1-py2.7.egg-info'