How can I change which commit master points to in git?

• stash your uncommitted: git stash
• create a new branch: git branch new_branch
• reset master to origin/master: git reset --hard origin/master
• checkout the new branch again: git checkout new_branch
• unstash your changes: git stash pop

stash/unstash is not necessary if your working tree is clean. just make sure there are no changes in your working tree, because those will be removed when you reset --hard

another possibility (faster, and without the need to stash and reset):

• checkout a new branch: git checkout -b new_branch master
• create a 'new' master branch and point it to origin/master's commit: git branch -f master origin/master

$ git checkout master
$ git reset --hard <commit-id-for-master-to-sit-at>

for example try this

$ mkdir example; cd example
$ git init
$ vi testFile.txt
(now add "test commit 1" to line 1 of file)
$ git add *
$ git commit
(add message "(+) 1st commit" to git commit)
$ vi testFile.txt
(now add "test commit 2" to line 1 of file)
$ git add *
$ git commit
(add message "(+) 2nd commit" to git commit)
$ vi testFile.txt
(now add "test commit 3" to line 1 of file)
$ git add *
$ git commit
(add message "(+) 3rd commit" to git commit)
$ git tag final_head
$ git reset --hard HEAD~1

this example shows moving the master to a different commit. Note here that the tag allows us to save the old master, in case :)

Go to .git/refs/heads/master which has the hash of master and change that to whatever you want. I use gitg to quickly find the hash of master and afterwards to verify that the move was successful.