Building a plugin to display (and remove) all the missing properties in Episerver isn't a fresh idea, in fact, I lifted this from a blog post by Per Nergård from 7 years ago (wow)! Still, I remembered it was useful and given that the code is no longer available I thought why not stick it in a gist.
The code isn't exactly the same as the original, I updated it to remove the (now) obsolete usages of the PageTypeRepository and BlockTypeRepository (the IContentTypeRepository covers both now). There are a few other smaller tweaks but for the most part it's still recognizable (and for the most part I can’t remember what they are).
The plugin lists all the properties that are missing from Episerver across all pages, blocks and media types (I just remembered this is a new addition!) and allows you to very conveniently bulk delete them.
To save myself describing it any more here it is as an animated GIF:
You can now find all the code for the plugin in this “Missing Properties” gist.