I recently borrowed a Garmin 510 from a friend and all his data has been uploaded to my profile. How can I delete all the data that was recorded on this device and retain all my data that was recorded on the my Garmin 810?
Thanks
You can't instruct Garmin Connect to find them for you and group them into a single batch for deletion, if that's what you mean.
You can manually select multiple activities listed on the Activities page in Garmin Connect online, then delete them as a batch. If you have no way of identifying them – for example, by the activity name – you may have to go through each activity record, and either change the activity name or (if you're not in the habit of marking certain activities as Favourites) use the Favourite marker, or attribute a dummy ‘course’ against the activities you want to delete, before going back to the Activities page and deleting them several at a time.