WHMCMS gives you the ability to rename this file to anything else as you need, but it's important to update that name in module settings page under "Client Area File Name" to match the real file name, also you will need to update .htaccess code manually if "Managed Rewrite Rules" is not set to automatic mode.
WHMCMS Dashboard will notify you if this file is missing, misconfigured or outdated, so make sure you visit it after doing an upgrade or doing any settings change.