Cinnamon. Find the openings (usually a few) and pour cinnamon in. Followup the next day with cinnamon mixed with water - make the solution strong. Sprinkle cinnamon around your yard. Reapply after rain.
You can also spray or pour peppermint oil around the opening to the warren, but do not use on your grass or plants as it will kill them.
Had a big, bad rabbit problem losing a prize Japanese maple and specialty quince. Cinnamon did the trick after trying several other methods.
Good luck!