Hi, welcome to Just Answer. I will help you with your question.
Thank you for you question.
I'm afraid there is no cooling off or cancellation period from entering into a guarantee. However, it might be possible for the person you've guaranteed to pull out of their agreement but that depends on the terms of their contract/lease with their landlord.
It could, however, be possible that the wording of the guarantee might release you if there is another agreement, or a variation of the present agreement, entered into with the landlord and tenant. This could include such things as a rent change, frequency of payment change etc.