Delete texture.

[Mike Amos]

Instead of deleting a colour/texture and replacing it with the default, how about replacing it with a selected colour/texture?

[TIG]

The plugin exists.
https://sketchucation.com/pluginstore?pln=Global_Material_Change
You get two lists of materials - select a target material and select a replacement material.
Everything having the target material then gets the replacement material...

[Mike Amos]

Thanks TIG, a pity just about everything has to be via a plugin but that's life. I will have to check that plugin.