To have push access on your repository, you can clone a git repository over SSH or HTTPS.
Current git version, doesn’t ask for username then
git clone https://mydomain.org/project.git
will fail with this error:
error: The requested URL returned error: 401 while accessing https://mydomain.org/project.git
Error 401 means the client is not authorized to access to that resource.

The solution is to clone the repository putting the username in the URL:
git clone https://username@mydomain.org/project.git

The git command to use is “revert”. But before to use it we have to figure out the commit that contains the “merge” and that we want to revert.
For this purpose we use “git log HEAD~X -Y” where X = [0-N] and Y = [1-N].
Once you know X and Y, “revert” command rolls back changes: “git revert HEAD~X -mY”.
At the end the reverting commit can be pushed to the remote server with “git push”