@LeNore24 As @Helen3 advises, I would message the guests and tell them it appears the security system has been turned off, and that, per the listing, it is there for the protection of hosts and guests and that it needs to be turned on ASAP.
If you have anything in your listing that says visitors aren't allowed then I would reiterate that to the guests [if not, I would add it].
You could also tell them if they are not comfortable with your house rules that you are happy to contact Airbnb to help facilitate a cancellation for them.
Depending on how close to the listing you live you could tell them that if the security system isn't back on in XX that you and/or your representatives will be arriving at the property to inspect and hopefully repair the system and you want to work with them to schedule a time for this that is convenient.