is it possible to delete related object related i.e delete child records when parent record is deleted using flow and process builder
You cannot start process by porcess builder on record
delete. It will start only when record
You need to have a trigger for the same to handle deleted parent record ids and delete related child records.
Please upvote this idea https://success.salesforce.com/ideaView?id=0873A000000LlbtQAC