We have bulk contact approx 1 million and we want to delete these all contacts from the marketing cloud so how we can delete these contacts from marketing cloud?
You can delete up to 1 million contacts per operation.
When deleting a large number of contacts, the delete process can contain no more than one million records.
You can automate the deletion process using SSJS. You need to populate a sendable data extension with Contact Keys you wish to delete (max 1 million at a time) and execute the call to Contact Deletion Framewok API. I have provided the code to do so, in my reply in this thread: Marketing Cloud SSJS: trying to automate contact deletion