There is a facility to cancel Material Requests, Requests for Quotations, which is available to the Supply Chain Manager at the bottom of each of the respective major screens in a section called "Hidden for SCM"

The action of this button is to write an audit record, where a note has to be made as to why it is cancelled, and the Status of the RFQ is set to "RFQ Cancelled".

Once the corresponding RFQ has been cancelled, then the same process must be repeated for the Material Request.