In VTiger 7 open source, there's no way to trigger a notification if a record is deleted from CRM by a CRM user. We came up with this customization that allows to send email or trigger workflow upon the deletion of a record in VTiger.
For article: https://www.vtexperts.com/how-to-set-...
For more customizations: https://www.vtexperts.com/vtiger-blog/