Lazy simple version for forgetfuls like me:
git rebase -i HEAD~3
or however many commits instead of 3.
Turn this
pick YourCommitMessageWhatever
pick YouGetThePoint
pick IdkManItsACommitMessage
into this
pick YourCommitMessageWhatever
s YouGetThePoint
s IdkManItsACommitMessage
and do some action where you hit esc then enter to save the changes. [1]
When the next screen comes up, get rid of those garbage # lines [2] and create a new commit message or something, and do the same escape enter action. [1]
Wowee, you have fewer commits. Or you just broke everything.
[1] - or whatever works with your git configuration. This is just a sequence that's efficient given my setup.
[2] - you'll see some stuff like # this is your n'th commit a few times, with your original commits right below these message. You want to remove these lines, and create a commit message to reflect the intentions of the n commits that you're combining into 1.