Been having an annoying issue for a while which this feature would go a long way to ease ...
I have several sections which are created as "home movies". This is because they contain video files which do not fall under TV series or Movies and do not have metadata sources to handle them. For example this can include rips of concerts or music videos off of DVDs (using handbrake). As I don't have an appropriate meta source for them I add these files in as appropriately named "home movies" sections in Plex which then scans them and displays them as a list related to their filenames (annoyingly losing any hyphens in the process).
Now 99% of the time this works fine with the system finding the local files and listing them in the section. The problem occurs when I need to make a change to the files outside Plex. This can be due to there being a typo in the name which should be addressed or moving files around and changing their names. The trouble with this is that Plex seems to remember the name the file originally had when it was first scanned in (I assume due to wanting to keep playback status info etc) and thus rescanning in the file does not change the displayed name to be the new updated name but still displays it with the original name even though it is linking through to the updated filename. This means each file then has to have its entry edited through the web interface manually to reflect its new name. I had this the other day is a large way with my music videos where I had wanted to move and rename them to give them a more organised structure but the system still picked them up as the old filenames.
Now this of course only really affects "home movies" as the normal TV series and Movies sections will manage this sort of thing by their usual metadata lookups.
My feature suggestion would be to have an option which can be set (tick box unset by default), particularly for sections of this type, to drop all held information for affected files from Plex if the file is removed thus allowing any rediscovery to start from scratch. I suspect that this would require a change so that the command used to drop the references to the file from the database was more complete if the option was set. The option may be wanted to be set at on a per section basis.