The folks over at Garmin have not been idle. It was announced yesterday that you can now edit your logs on opencaching.com. Now you can delete and edit your logs. This is a much needed improvement. I contacted Garmin last year and asked how I could delete my logs and was told that I couldn’t. I’m pleased to see that users have more control over their data. Cache owners can also delete logs. [note: this post was updated based on comments]
The ability to edit logs is not yet available to third parties using the opencaching API.
You need to navigate to a cache you have found. From their you will see the edit option. In the image below you can see the options available for editing. If you have previously uploaded your my finds file you can now go back and edit your previous listings.