I was helping a friend with his 605 today to install a course. Unfortunately, the device auto-synced, dumping his 5 years of activities into my profile/account. I can't seem to find any way to ask Garmin about this - Strava fixed it in less than an hour based on the fact that all my friends activities were recorded on a 605 - which I have never used.
Any tips, or is my entire 6+ years of GC history now garbage?