If you are receiving a lot of spam emails to email addresses that you don't have set up on your account, disabling the default address is recommended.
Log into your cPanel account. If you are unsure on how to do this, please view the following help article - 'How to log into cPanel'.
Once you have successfully logged in, scroll down to the 'Email' section as per the below. Select 'Default Address'.
Choose the option to 'Discard the email while your server processes it by SMTP time with an error message...'. This will send a response back to the sender that no such email account exists.
Choose 'Change' to complete the process.
Disabling the default email address is now complete.