I have 2 websites sharing the same Magento 2 install. I have data in the short description on one store that I don't want to use anymore as I have the short description defined correctly at All Stores level. How can I check the box on short description for all the products in the one store to have it use 'default'?
If you're asking for a "quick" way to have the stores use the default/website values again, then you'd be looking for a way to actually just delete the data at that store scope; the absence of store scope data implies that it should fall back to the default/website values.
Essentially you'd be wanting to remove data from tables like such (please, for the love of god, take a DB backup before running anything like this...):
DELETE FROM `catalog_product_entity_text` WHERE `store_id` = 2
catalog_product_entity_text is the table containing all text attribute data for products, and
store_id is of course the store view's ID number. This would remove all text attribute data for products on that store view.