If You Need To Edit Or Change NS On Your Server You Should Follow This Steps:

              1 - Firstly you need to login to your WHM Control Panel 

              2-  From 

• Home /
• Server Configuration /
• Basic WebHost Manager Setup
  
                              
  
  3- Choose Basic WebHost Manager Setup 
  
  4- Scroll Down 
  
  5- From There You Can Add Or Change Your Nameservers
  
                               
                                   
  6- The last Thing Click On Save Changes To Save