Hi Jennifer, we have the same issue, no kids, especially free infants up to 2 years (which is not an infant they are a toddler and toddlers toddle...and make a mess that we then clean up for free).
We have the details of age restrictions clearly outlined in our 'Other Things to Note' section because guests can see this pre-booking, if they read that far down. If they book after that, you can ask them to cancel within 48 hours for a full refund. You shouldn't need to cancel from your side as this would penalize you. If you call support, they should be able to cancel the booking or eliminate the request without penalty to you.
Caveat, not all support agents are created equal and may offer contradictory recommendations to those above...I might have gotten lucky a couple of times with informed agents.