Is it a manual or smart collection? If manual, you can select in batch on the Products page and do the following:
Let me know!
I need to use the api and I need to loop through the products to delete them using collectionRemoveProducts. There isn't the ability to delete the products through say a wildcard, delete all, leaving the empty collection in place.
Using collectionRemoveProducts will be OK for me, as the collection will only have 100 or so items, I should poll the job to see when it has finished, as mentioned in the docs