Large Plex Media Server Folder

Is there a way to make this folder smaller or clean it up? I have it on its own drive which is 476 GB & there is only 189GB free. It seems to be getting bigger every day. Any thoughts?

In Settings - Server - Library, change
Generate video preview thumbnails
Generate chapter thumbnails

to Never

Also, in the Advanced tab for each media library section, is the box Enable video preview thumbnails checked?
If so, uncheck it and then click Delete Preview Thumbnails

Thanks @ChuckPA!