You can decline any request that you are not interested in by opening the request and clicking the red Decline button in the top middle of the request.
You will be prompted with different decline reasons that you can choose to why you want to decline the request. You should always use the decline reason that most closely resembling the truth of why you want to decline it. This way the data gets adjusted automatically, reducing the chances you will get deals you want to decline in the future.
A declined request is visible on your request page for 7 days before it is deleted. In case you need information from a declined request, please reach out to xChange.