8014568b_cle_Database_with_Arun_Kaushik__Delete
[Point] 6. Referential Integrity Constraint Behavior [Truncate] We can’t truncate a table with enable Referential Integrity Constraint, even there is no data in the child table, we have to disable or drop the constraint if we want to truncate the table. Exception: Truncate is possible if the FK is self-referential means primary key and foreign key are on the same table. [Delete] 
if we don’t have related data in child table then we can delete the data from the parent table or we have variants like On Delete Cascade & on Delete set Null. For more details see listing 4
Dive in Oracle Database with Arun Kaushik
Delete