Tried adding a custom ACL to disallow DELETE as per
https://enricosimonetti.com/powerful-customisations-with-sugars-acl/
but this does NOT seem to work when I try it on Sugar 13.0.3
custom\Extension\modules\Contacts\Ext\Vardefs\acl.php
custom\data\acl\SugarACLDenyDelete.php
Can anyone point me to a way that works in v13+?