How to delete a scheduled task using Rules Scheduler? I use the rules scheduler module (D7). So far all fine.

What I use it for:


a user registers with username and email
this users then gets 4 emails over the next four weeks, sent by the scheduler


BUT: In case a user wants to unsubscribe from these scheduled emails? How can I achieve it?

It is true that one can delete particular sort of scheduled tasks with the according action (Delete scheduled tasks). But I don't know how to indicate it shall only delete the tasks that are related to a particular?

When I list the schedule with ...
/admin/config/workflow/rules/schedule

... there is one column called "USER PROVIDED IDENTIFIER" - maybe it would help to do it with such an identifier. But I don't know how?

UPDATE TO THE QUESTION:

I tried to import with the suggested changes, this is how my rule looks like now:

{ "rules_user_reminder_after_30_days" : {
"LABEL" : "User Reminder After 30 Days",
"PLUGIN" : "reaction rule",
"OWNER" : "rules",
"REQUIRES" : [ "rules", "rules_scheduler" ],
"ON" : { "user_login" : [], "node_insert--article" : { "bundle" : "article" } },
"DO" : [
  { "schedule_delete" : {
      "component" : "rules_send_email_notification",
      "task" : "[account:name]"
    }
  },
  { "schedule" : {
      "component" : "rules_send_email_notification",
      "identifier" : "[account:name]",
      "param_user_to_notify" : [ "account" ]
    }
  }
]
}
}


But now I got this error: 


  Integrity check for the imported configuration failed. Error message: Missing configuration for parameter date
Have a look at my answer to "Rule to store user&#39;s last post date and scheduled rule based 30 day reminder" for an illustration about how to delete scheduled tasks, using the "schedule_delete". As explain in that answer: the schedule_delete that is part of this rule is to ensure that previously "scheduled" reminders will get removed when updating the data field (so that it only triggers 1 reminder, and with the most recent date).

To make this work (that you actually indicate the exact scheduled task to be deleted), you need to specify an appropriate "identifier", like "[account:name]" in my example. To understand how I know what in my case the identifier is of the task to be deleted, look at the way I specified my (new) scheduled task to be created: it is "identifier" : "[account:name]", which  is what I used as my identifier to schedule a task.

In your case, I think "[account:name]" would be a pretty good choice for such identifier. But your questions states "... users then gets 4 emails over the next four weeks, sent by the scheduler ...". So if the 2nd email only gets scheduled after the first email (and not schedule all 4 emails upfront together), and similar for the 3rd and 4th email, then you should be fine using this identifier also.

Note: Specifying an "identifier" like "[account:name]" is what you'd do in your Rules Action (similar to my "step 3" in the above sample). While you'd probably want to create a Rules component similar to my "step 2" in the above sample to actually send an eMail.

Update: The "integrity check" problem shown near the end of the updated question, is probably because in your rule, as shown in the updated question, does not specify the date to schedule your component. Have a look again at my answer I mentioned above: the rule there specifies a date via this part of it:

  "date" : {
    "select" : "account:field-next-article",
    "date_offset" : { "value" : 2592000 }
  },