Thanks for your help .
I want to write a trigger that acts like this:
When a user executes a DELETE statement, the trigger must set the WhenDeleted value to the system’s CURRENT_TIMESTA MP value, for each of the rows targeted by that DELETE statement....

I want to write a trigger so that rows deleted from the table are logically-deleted, rather than being actually removed. That is, such rows are marked as being deleted, rather than actually being deleted from the table.

in sql server I know that we can use INSTEAD OF DELETE trigger but I don`t know how can I do the same action in PostgreSQL.

It needed to write a function that update the rows which asked for delete....