Destructions require that source lots contain an amount of weight equal to or greater than the amount being transferred to a destruction lot. In other words, a Grow Technician cannot destroy more weight than they have harvested during the harvest workflow. This ensures that the weight is properly recorded and traceable for Health Canada's required reports.
Solution:
Change harvest mode to Weigh no Plants.
Harvest the weight you're trying to destroy.
Transfer weight to a destruction lot.
Learn more about Harvesting Plants.