Remove gauge metric #1055

Hi all,
I have written a custom exporter for calculating the cost of using a node in AWS.
Here is how it works:
Lets assume I have 3 nodes, each costs 5$/ 1h, when I plot using grafana the sum(cost_metric{}) i get 15$ (3x5$). Lets say after 2 hours one of the nodes get deleted (autoscaling). In that case the total cost should drop to 10$.

The problem is that in my case the metric is preserved and even though the node has been deleted the cost is kept and thus it displays 15$ instead of dropping to 10$

How would I go about saving that problem?

cost_metric = Gauge(
    "cost_metric ",
    "Cost of running an instance for 1 hour",
    ["node_name", "instance_type"],
)
...

node_names = get_nodes()
    for node_name in node_names:
        node_info = get_node_info(node_name)
        if node_info is None:
            continue

        logging.info(f"Updating metrics for node: {node_name}")

        # labels section
        labels = node_info["metadata"]["labels"]
        instance_type = labels.get("beta.kubernetes.io/instance-type", "unknown")
        cost = get_cost_of_instance(instance_type)

        if cost is not None:
            cost_metric.labels(node_name=node_name, instance_type=instance_type).set(cost)

I tried

I collected previous and current nodes in form of dict and then wanted to removed the ones that arent existing, the issue is that :

cost_metric.remove(node_name=node_name, instance_type=instance_type)

Traceback (most recent call last):
  File "/home/XXXX/projects/main.py", line 154, in <module>
    previous_nodes = update_metrics(previous_nodes)
                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/eksohio/projects/main.py", line 131, in update_metrics
    cost.remove(node_name=node_name, instance_type=instance_type)
TypeError: MetricWrapperBase.remove() got an unexpected keyword argument 'node_name'