In AE5, the pull button works only for shared projects as explained in our collaborating on project docs. To revert to the previous change from your non-shared project, you can use git revert from the Terminal to undo the commit or roll back to the previous commit.
You have to use the default environment's Terminal for this. For the Python 3.6 project, anaconda50_py36 is the default environment.
Please run the following commands from the Project Terminal:
git checkout master
git log --oneline
#it will show <last commit hash> <commit message>
git revert <last commit hash>
#This command will create a new commit with the “Revert” word in the beginning of the message
git push origin master
#push the local changes