Remove untracked files from the working tree.

# To delete files that are not tracked by git:
git clean

# To interactively delete files that are not tracked by git:
git clean -i

# To show what files would be deleted without actually deleting them:
git clean --dry-run

# To forcefully delete files that are not tracked by git:
git clean -f

# To delete untracked files, including ignored files in .gitignore and .git/info/exclude:
git clean -x