@Betz0 you did not make any error.
If the button used to say "Pre-Approve" and the button now says "Withdraw Pre-Approval" then you have sent your Pre-Approval already.
So since the button said "Pre-Approve" earlier, that means your prospective guest sent you an Inquiry, which is really just them asking questions about booking with you. They did not send an actual request to book with you, they are just asking questions.
You do not have the option to "Approve" because you can only "Approve" a Booking Request.
The only thing you can do with an Inquiry is to "Pre-Approve" them, which you already have done