To deny a resource request, log on as the approver (resource manager in this example) and navigate to the resources tool. There is also a pop-up notification, and the same notification can be seen when clicking on the notification icon.

Check the notification, then click 'Open'.

Here the resource manager would check the request details by clicking on the view icon and decide to either approve, reassign the request, or reject it (in this case, reject request).

In case you're not satisfied with the request details, click ' Close'. Hover over to request, click on 'Manage' and select 'Reject request'.

Here, the resource manager is able to define a reason for declining the request. Once you've done that, click on ' Yes, decline request'.

The status of the resource request changes from ' Request pending' to 'Request rejected'. 

As soon as the resource request is rejected, a notification will be sent to the original requestor to inform about the rejection. See more info in the following article about Responding to a request denial and edit the assigned resource