Instead of deleting tasks, we recommend that you do a Reset if you simply wish to have the task reset as it was when you first created it, but we do recommend using caution with Reset and Delete.
Should you change the underlying data significantly or you wish to try a fresh sync, on FitnessSyncer.com, you can try clicking the Edit () button from My Account on the task in question and clicking Reset Task from the toolbar. When this completes, click Sync () again.
It should be noted that Resetting a task will delete all of your data associated with the task and if you have done any Historic Syncs or anything to that nature, you may need to reissue those. This feature is also not available in our mobile apps at this time.