For the longest time the stock Rekordbox samples have annoyed me. To me it seemed like you could not delete them, until I learned today. So I'm sharing this with you!
Written instructions:
Open RB and remove samples from library. Go to program files (for me its C:\Program Files\rekordbox\rekordbox 7.0.5) and delete or rename the file GROOVE_CIRCUIT_FACTORY_SAMPLES.spp. That should do it!
Hope this helped!