title: Wordpress add custom roles as well as remove default roles
body: <p>I need to customize the default roles as I need only 3 roles <code>- administrator, buyer, seller</code>. </p>
  
  <p>Then I need to add the buyer, seller and remove all other default roles. What should I do? </p>
  
  <p>If there is any ready made code which I can paste in and it will work?</p>