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Navigate to the Catalogues option under Purchasing - if there are any catalogues requiring authorisation, these they will be listed along with any previously authorised catalogues:
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You have the option to Approve All changes an install the new catalogue update, Decline all changes to the catalogue, or you can tick individual items and decline only the selected items. when When selected a pop up box will be displayed requiring a reason for the decline:
Information provide The information provided on the Decline Notes will be presented to the Supplier reasoning , giving the reason why these have been declined.
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