Suspension takes an account offline without deleting anything, which makes it the right tool for non-payment.
SUSPENDING
WHM > Account Functions > Suspend/Unsuspend an Account. Select the account, enter a reason, and suspend.
The website stops loading, email stops being delivered, and the client cannot log in to cPanel. All files, databases and mailboxes remain intact.
UNSUSPENDING
The same screen. The account returns to normal immediately.
DOING IT FAIRLY
Tell the client before suspending, not afterwards. A clear reminder sequence with dates avoids most disputes. Record the reason in the suspension, so you know months later why it was done. Consider whether email should go down too. For a business client, undelivered email causes more damage than an offline website and generates the angriest calls.
AUTOMATING IT
A billing system can suspend and unsuspend automatically based on invoice status. Set the timing deliberately.
WHAT NOT TO DO
Do not terminate for non-payment as a first step. Suspension is reversible; termination is not, and a client who pays late is still a client.