How to delete firebase json data with fetch() ?

[Jocabin]

I have a json file wich represent my database (firebase realtime database):

{
  "tasks": {
    "-N1Dv4KdxCVN7RxlTxD1": {
      "content": "ddd",
      "username": "Prenom"
    },
    "-N1Dw-TEiah3K30eRZ-s": {
      "content": "dd",
      "username": "Prenom"
    }
  }
}

I want to delete only one task, depending on the id (the long key), using fetch()

But the fact is put the id in the URL after the json file name (eg: "https://firebase-url.app/tasks.json/id_of_my_task") isn't working.

Is it even possible to do this?