@Áine10 I don't think you understand how any of this works. You should never have to cancel a booking request. You need to dialogue with the guest before you decide whether or not to accept a booking, and if you don't feel good about their answers or communication, you decline the booking. Then you never have to cancel.
And do you understand the difference between an Inquiry and a Request? Most of these scammy attempts to book off-platform or ask for a discount come in the form of an Inquiry message. On inquiries, you do not need to either pre-approve, nor decline- all you need to do us answer within 24 hrs.
So what happened here? You got an Inquiry, pre-approved it, and then cancelled it?
FYI discount seekers are red flags and there is no reason for you to agree to discount.
Someone who asks for a discount and to pay off-platform is a huge red flag and never should have been accepted in the first place.