Dedicated ip ,, and name server dns on VPS

i’v One Vps with main domain Main.com with name server and ip

ns1.main.com 192.168.1.1
ns2.main.com 192.168.1.1

i host many websites under this vps and need to hide from competitors , so i assigned dedicated ip to each domain ..

domain.com 192.168.1.90

but in who is the site reefer to name server ns1.main… ns2.main

and the main ip .. so any one can trace all sites under this vps with the main ip ..

how to hide the name server or at least show it as ns1.domain ns2.domain … ?

i need to be unique name server to everydomain and hide all possible tracking ..

thanx