Expertise level: Easy
WHM has a utility to transfer multiple accounts from another WHM/cPanel server. Use the following procedure to transfer accounts in bulk from another server.
Start by logging into WHM as root.
Open the "Transfers" section.
Click on "Copy multiple accounts/packages from another server".
Enter the remote server's login details.
Click on "Fetch account list".
Pause for a moment to allow WHM time to download the list of available accounts. Select the accounts and packages that you wish to import.
Click on "Copy" to start the transfer.
It will take some time to complete the transfer, depending on how much data is stored in those accounts.