If a HEAD has to be reset to a older version this is a possible workflow.

The solution is from stackoverflow

First checkout the version that should be the new HEAD.

git checkout <SHA-1 id of commit>

Now we create a temp branch and check it out.

git checkout -b temp

This is equivalent to git branch temp followed by git checkout temp.

Now we want master (or an other branch) to point to it.

git checkout -B master temp

This is equivalent to git branch -f master tempfollowed by git checkout master.

Now we can delete the temp branch:

git branch -d temp

Now we can push to a remote (-f might be needed):

git push -f origin master