How to edit a CloudWatch Metric?

CloudWatch metrics themselves cannot be directly edited or modified once they are created, as they represent data points collected from your AWS resources and services. However, you can modify how metrics are used in different contexts:

For CloudWatch Alarms: If you want to change the metric associated with an alarm, you can edit the alarm configuration:

1. Open the CloudWatch console and navigate to Alarms
2. Select the alarm you want to modify
3. Choose Actions, then Edit
4. On the Specify metric and conditions page, choose Edit
5. Select the All metrics tab and choose a different metric by browsing the service namespace or searching for a specific metric name
6. Select the checkbox next to the desired metric and choose Select metric

For Dashboard Graphs: To add or modify metrics on a CloudWatch dashboard graph, you can edit the JSON source:

1. Navigate to your dashboard in the CloudWatch console
2. Choose Actions, then View/edit source
3. Modify the JSON block to add or change metric definitions, including the namespace, metric name, and dimensions
4. Choose Update to save your changes

Using Metric Math: You can also create metric math expressions that transform or combine existing metrics without modifying the original metric data. This is useful for creating custom calculations or suppressing data during specific time periods.

Remember, the underlying metric data itself remains unchanged - you're modifying how the metric is referenced or displayed in alarms and dashboards.
Sources
Edit or delete a CloudWatch alarm - Amazon CloudWatch
Graph metrics manually on a CloudWatch dashboard - Amazon CloudWatch
Tutorial: Use a metric math function to suppress an alarm - AWS Incident Detection and Response User Guide