git reset remote branch.md

Assuming that your branch is called master both here and remotely, and that your remote is called origin you could do:

git reset --hard <commit-hash>
git push -f origin master

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Use the other answers if you don't mind losing local changes. This method can still wreck your remote if you choose the wrong commit hash to go back to.

If you just want to make the remote match a commit that's already in your local branch:

git push --force <remote> <the-hash>:<the remote branch>

e.g.

git push --force origin 606fdfaa33af1844c86f4267a136d4666e576cdc:master