Firestore! How can I remove a map from array by javascript code?

I am trying to remove a map form an array in Firestore by using Javascript Could any one help me with that?

By the way I used those several methods but none of them are working at all.

First method:

imgRef.update({
        "images": firebase.firestore.FieldValue.arrayRemove({
            "caption":...,
            "id":...,
            "postID":...,
            "url":...,
            "userID":...
        })
    });

Second method:

imgRef.update({
        "images": firebase.firestore.FieldValue.arrayRemove(0)
    });

Thanks for all your help