• Download all emails under the account to be migrated using a mail client like outlook express

• Download files backup & database backup of addon domain(or subdomain or main domain) with the help of a developer

• Delete addon domain(or subdomain or main domain) from Cpanel or Reseller WHM

• Recreate the domain as main domain(or addon domain or subdomain)

• Recreate all email accounts in new addon domain(or subdomain or main domain). Please note that emails cannot be migrated to new account & it will remain in mail clients like outlook express

• Upload all files to new main domain(or addon domain or subdomain) using FTP

• Recreate databases in new main domain(or addon domain or subdomain)

• Restore databases either using phpMyAdmin

• Modify configuration files in the website to reflect new database names & user names

• Check websites & ensure that it is working fine under new main domain(or addon domain or subdomain)