How to delete Multi-Material collections?

[Dave@DRAFT]

I have a very large and complex Keyshot file with multiple studios and hundreds of parts.

Within the Studios window there are a whole ton of Multi-Materials in the drop down box. Most of these need to be deleted / removed but I can't figure out how to do this.

There are about 25 multi-material ...clusters or whatever you call them, and there should only be about 3.

[Will Gibbons]

Find the in-scene materials list. You can sort them there. But since materials can't be 'deleted' from parts, you have to apply something over them or link them to something else.

[INNEO_MWo]

Just close the multimaterial by the button and only the applied instance will be as active material