git push rejected: error: failed to push some refs

git push -f if you have permission, but that will screw up anyone else who pulls from that repo, so be careful.

If that is denied, and you have access to the server, as canzar says below, you can allow this on the server with

git config receive.denyNonFastForwards false

If you are the only the person working on the project, what you can do is:

 git checkout master
 git push origin +HEAD

This will set the tip of origin/master to the same commit as master (and so delete the commits between 41651df and origin/master)

'remote: error: denying non-fast-forward refs/heads/master (you should pull first)'

That message suggests that there is a hook on the server that is rejecting fast forward pushes. Yes, it is usually not recommended and is a good guard, but since you are the only person using it and you want to do the force push, contact the administrator of the repo to allow to do the non-fastforward push by temporarily removing the hook or giving you the permission in the hook to do so.

Just do

git pull origin [branch]

and then you should be able to push.

If you have commits on your own and didn't push it the branch yet, try

git pull --rebase origin [branch]

and then you should be able to push.

Read more about handling branches with Git.