That means to remove it from:

• README.rst
• CONTRIBUTING.rst
• .pre-commit-config.yaml
• .travis.yml
• appveyor.yml
• setup.py
• tox.ini
• all tests (hihi)

We can even think about dropping all the python2 workarounds we have in the library itself:

• remove future from requirements and all the imports
• _UTC in telegram.utils.helpers
• Workaround in telegram.InputFile.__init__()
• from builtins import str in telegram.utilts.request
• test_send_on_server_emoji
• imports in test.updater

(This list is not comprehensive)