La nueva version de garmin conect no me permite eliminar del calendario la sesion de entrenamiento y adjuntar otra nueva

Other than translating to English, I can't help much.  But you might be better served by putting your content into the appropriate Garmin Connect area.  Go to "Apps & Software, then chose the best choice.

"The new version of garmin connect does not allow me to delete the training session from the calendar and add a new one."