xxxxxxxxxx
git rm --cached /path/to/file
git commit -am "Remove file"
git push
xxxxxxxxxx
git reset --soft HEAD^
or
git reset --soft HEAD~1
git reset HEAD path/to/unwanted_file
git commit -c ORIG_HEAD
xxxxxxxxxx
git reset --soft HEAD~1 #gets your files back to staging area
git restore --staged files/you/want/to/unstage #removes the files from staging
git commit -m "Continue with commiting the remaining set of files"