When submitting a pull request, it’s highly suggested to squash your commits down to a few, or one, discreet changesets.

To do that, the below example shows the detailed steps:

Now I have added three commits in a Git repository as below

Next, let’s start the squash. First go to the home folder of git repository. Then run the command

# there're 3 commits, so `HEAD~3` here
git rebase -i HEAD~3

You can see below prompted message

pick 37ff3bd commit1
pick 32756c4 commit2
pick a13ca74 commit3

Change the word pick to squash except the first line, like

pick 37ff3bd commit1
squash 32756c4 commit2
squash a13ca74 commit3

After save a new commit is ready, and you can update with another commit comment like:

squash 3 into 1
# This is a combination of 3 commits.
# This is the 1st commit message:
commit1

# This is the commit message #2:

commit2

# This is the commit message #3:

commit3

Now run the git push command

git push --force

Now in git repository, you would find that the previous 3 commits are replace by one squashed commit.