I have many workouts that synced from Trainingpeaks, my workouts cover 20 pages. I want to be able to select workouts and delete in bulk from Garmin Connect, and not one by one
I created a script for bulk activity deletion:
RE: Can I delete just the activities from a single Garmin device from my Garmin Connect account?
Since the original purpose was for deleting activities from the wrong device, the script requires you to specify a device ID for activities to be deleted. For training peaks activities, I am guessing that the device ID is 0 (as it is for manually created activities and workouts from certain 3rd party services), but you can verify that by following the instructions in the linked post.
The script also allows you to filter activities by criteria such as name and date, if necessary.
Unfortunately it doesn't allow you to graphically select activities for deletion.