If all transactions associated with a Suggested Recurring Item are deleted, the Suggested Recurring Item gets deleted, but the associated rule doesn't.
Similarly, if the transactions linked to a Suggested Recurring Item are linked to an existing Recurring Item by a rule, they will no longer be associated with the Suggested Recurring Item and the Suggested Recurring Item is removed. The associated rule remains on the Rules page.
The rules should be deleted if the Suggested Recurring Item no longer exists, even if deleted indirectly by removing the transactions or linking them to another Recurring Item.