Personal footprint library
Make a new project
Open the footprint editor (it will say no active library and you cannot save anything)
just choose a random library
Select: Save current libary as (and choose a filepatch and name for it. so you can find it again)
Go to "board view" and choose in Preferences -> Footprint library manager
add you custom library at the bottom, give it a good name and the location on your drive
Close KiCAD and Restart. Go to Board view and try "Add footprint", choose "Select by browser" and find your custom library.
Done! if you have all these footpring from your random choice above. go to the location and just delete all you don't want.