Git how to revert a merged merge request

 https://stackoverflow.com/questions/7099833/how-do-i-revert-a-merge-commit-that-has-already-been-pushed-to-remote

In git revert -m, the -m option specifies the parent number. This is needed because a merge commit has more than one parent, and Git does not know automatically which parent was the mainline, and which parent was the branch you want to un-merge.

When you view a merge commit in the output of git log, you will see its parents listed on the line that begins with Merge: (the second line in this case):

commit 8f937c683929b08379097828c8a04350b9b8e183
Merge: 8989ee0 7c6b236
Author: Ben James <ben@example.com>
Date:   Wed Aug 17 22:49:41 2011 +0100

Merge branch 'gh-pages'

Conflicts:
    README

In this situation, git revert 8f937c6 -m 1 will get you the tree as it was in 8989ee0, and git revert -m 2 will reinstate the tree as it was in 7c6b236.

To better understand what you're about to revert do git diff <parent_commit> <commit_to_revert>, in this case:

git diff 8989ee0 8f937c6

and

git diff 7c6b236 8f937c6