When you activate or deactivate a domain, the activation status affects all companies
within the domain.
When you activate a company record, domain separation automatically activates the
company's associated domain. For example, if you activate the ACME company, then you
also activate the TOP/ACME domain.
Navigate to the domain record.
Clear or select the Active check box.
Warning: Do not delete domains. Deactivate domains that you no
longer need instead of deleting them.