Adjust Whatsapp Share Media Option on Android

have an LG Stylo G and I use Whatsapp. Whenever somebody contacts me or vice versa their number remains as an option to share media with. This even happens with contacts which I no longer keep on my phone. So I need to find a way to remove all these past contacts so I dont have to face all the clutter of the many different options to share media with. These past contacts are removed when I clear the apps data so I am sure their must be a system app that keeps all this information. I just dont know which one it may be. Any Ideas. Thanks in advance.