I noticed Blender 2.79 doesn't show the "save & reload" option anymore. I used to use that to clear any unused materials. How can I do this? I tried making all objects single users, the orphan add-on, nothing seems to work.
As an alternative to the other answer, if the material isn't assigned to anything, select "orphaned data" in the outliner and expand the "materials" category. you can then right-click and delete any material you don't want anymore and it will be removed from the file immediately, no need to save and reopen.