I've found that it is fairly easy to delete an activity. Is there any way to delete a month's worth (or even a day's) of step data? I imported a bunch of data from my fitbit days that I have no use for and it is affecting my "records" and would like to delete the data. Is this possible?
I think the easiest thing to do is to open a second Connect account and start from scratch. Let the first one die. The only issue is you'll also lose some Garmin data as well.
You can edit (text editor) and re-import the Fitbit .CSV file, with the dates left as they were, and the stepcounts edited to what you want them to be, as long as the number is greater than 0. This is only possible if there is no data present originating from a Garmin device for that same day. I tried it to see if it worked to change the stepcounts, but did not look at the effect on overall stats, badges or records. I have asked Garmin a few times if they would consider implementing a way for users to delete their own fitness tracking data, they replied that "their engineers were thinking about it", but this thought has not yet resulted in a 'delete' option. Even if you have your Connect account removed, the fitness tracking data will stay behind, it will just not be linked to your email address anymore.