Remove unused master templates
Several request are about removing slide layouts that aren't used. This one is about removing Master templates that aren't used. People often repurpose a presentation and after multiple pastings, the deck gets multiple masters in it. At some point, many are not even used but bloat the file size. It should be an option to be cleaned up through something like optimization or the Inspector.
John Korchok commented
If slide masters get added, it's because the template was poorly designed. Here's an explanation: http://www.brandwares.com/bestpractices/2018/11/legacy-slides-brandwares-best-practices/