Follow me through the steps below to get it done:
==> Sign in to your account at DomainKing website
==> Click on "My Domains"
==> Click the small arrow next to the domain name you want to edit it's nameservers.
==> Scroll down to the Nameservers section as seen in the screenshot below:
==> Select "Use Custom nameservers"
==> Delete the Namesevers and replace with the ones provided by your web hosting company.
==> Click "Save Changes"
You can expect a propagation time up to 24 hours. This is because it takes time for the DNS to take effect across the internet. So, be calm.