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Quote - great, thank you. I have created a new material and all I want is to render the scene based only on the new material. Is that possible without deleting the other materials?

Each material zone can only support one material, though that one material may consits of many elements. So yes, you don't need to delete any materials. If you want the same material settings ("Shader") applied to all the materials in the figure, do as bagginsbill said. Set up one material the way you want it, then do 'Select All' > 'Apply to all' (see graphic above).