Disconnect a sync service?

@JamesChevalier,
I believe I had previously deleted the erroneous activity from Strava in the past, but it’s probably synced up and existing on either Runkeeper or MapMyRun (I’ve used all 3 services, and have my activities Sync to all 3).

Problem is, when I signed up to CityStrides, I attached all 3 services to my CS account… so therefore bad data that I’d previously cleared out of my Strava heatmaps is showing up here.
I can’t find a way to disconnect accounts - is this possible, or something you can do for me? I’d like to disconnect Runkeeper and MapMyRun from CityStrides in order to get CS to only use Strava data (since I’ve gone to the effort of cleaning up my Strava history, so it’s the only source I now trust).
And I guess the followup question will be - once those accounts are disconnected, will my activities connected to them be auto-removed? That would be good if so… otherwise I’d have to manually delete hundreds of activities.

If it makes things any easier - you could simply detach and wipe all accounts/activities from my account, and then I can re-connect Strava and CS could re-sync all of my (Strava-only) activities.

Sorry to be a pain - appreciate any assistance/advice!