How can I delete everything in my Keychain and get it to stay deleted? Ive tried but it just comes right back, and should I have public and private keys??

I have a lot of items in my keychain that I have no idea what they are. In all if them. Login keychain, system Keychain, and System root, Icloud as well. Obviously I know what the ones that are related to my accounts are and obvious system passwords and such, but a friend who is a Security Analyst took a look at my keychain and said my computer looked like it was set up like someone that worked in his field. Which it would have no reason to be being I dont do anything of the sort on my machine. Being there are Private and Public Keys and way to many certificates from very obscure places. Self signed private keys..... and when if I delete them , they immediately just come right back. Im hoping someone might take a look and tell me if they have these same things and how I might be able to get rid of them? For the record, Ive never had Find my mac turned on and the Account it has listed for it Ive never heard of. The certificate Ive included, isnt signed by a third party yet its usage is able to do quite a lot.

Thanks and Sorry if Im not doing this correctly, I just have been trying to get help with this for a while.