How to delete logs from Firebase Cloud Functions

Cloud Functions log retention is based on the standard Stackdriver limits. For free projects, logs are kept for 7 days. If you upgrade your stackdriver plan it's 30 days.

You can use Stackdriver's deletion api to delete the log entries. The log name for cloud functions should look similar to: projects/<project-id>/logs/cloudfunctions.googleapis.com%2Fcloud-functions" and can be found using the list api

That's just an addition to @Kiana answer.

You can see it directly within the Firebase console. When trying to choose the timestamp for the logs, logs older than 1 month are disabled, which means are automatically deleted. At least for project's owner, maybe Google stores it somewhere deeper in their logs.

Still, there's no option to delete the logs manually.

Edit: maybe it's good to add, but even if you'll delete your function, the logs of the deleted function still will be there for 1 month.