@Janice271 : Greetings fellow Minnesotan!
While I understand and agree entirely with your offense at a guest breaking house rules and violating the law, Airbnb is not a law enforcement entity (nor very supportive of hosts if you don't have physical damages). Unfortunately, you'll have to just bite the proverbial bullet, clean the mess, and move on. This tends to be the outcome for most hosts with smoking-related violations (illegal or not).
Your best recourse is to write an honest review to warn future hosts and rate the guest(s) as not being welcome at your listing again.
Another option may be to file a report with your local law enforcement agency if you have pictures or other evidence, but often times, this isn't a priority case for them.
Now go enjoy this beautiful weather!