Delete subform lines automatically

If you need the system to automatically delete records in related tables when a record is deleted in a certain table, you need to program this in the table's OnDelete trigger.

Albert's suggestion of looking at the Sales Header table is an excellent example. Open the table designer for this table, and look at the C/AL editor. Start at the top of the code and scroll down until you reach the OnDelete trigger. In here you will see everything that happens when a record in the Sales Header table is deleted by a user (i.e. on a form).