General usage for cleaning your working directory of untracked files:

$ git clean [-d] [-f] [-i] [-n] [-q] [-e <pattern>] [-x | -X] [--] <path>...

Config setting:

• clean.requireForce

Prerequisites: gitignore

Cleans the working tree by recursively removing files that are not
under version control, starting from the current directory.

Normally, only files unknown to Git are removed, but if the -x
option is specified, ignored files are also removed. This can, for
example, be useful to remove all build products.

If any optional <path>... arguments are given, only those paths are
affected.

General execution options:

-i, --interactive
    Show what would be done and clean files interactively.

-n, --dry-run
    Don’t actually remove anything, just show what would be done.

-q, --quiet
    Be quiet, only report errors, but not the files that are successfully removed.

Forcing the issue: