git force existing branch to specific commit code example

Example 1: git move branch to previous commit

git checkout 1258f0d0aae    #detach from master
git branch -f master HEAD   #exactly as above

#optionally reattach to master
git checkout master

Example 2: set head of branch at specific commit

# You can make master point at a specific commit this way
git checkout master
git reset --hard <commit-hash>

# git reset --hard command will throw away any uncommitted changes 
# (i.e. those just in your working tree or the index).