I’ve done a lot of noise recordings and want to clean up. How to delete noise recordings?

First, a good thing to have is auto-delete, which will delete your noises automatically after one week. This is enabled by default in Settings > Noise recording.
Second, you can go to the noise tab, click one of the noises and use “Delete all unstarred recordings”.
Also if you are getting too many noises from the night, you may consider a higher recording threshold in Settings > Noise recording.