Bulk editing Store Categories is available for published, ready to publish, failed to publish, and needs review listings within the eBay channel.
To access the bulk edit tool, navigate to Listings, then select the listing status tab, then select the listings you would like to edit.
Next, select the arrow button to bulk Edit store categories for the selected listings, or select Publish to eBay.
Select from the list of existing eBay Store Categories, select Continue.
New eBay Store Categories may only be created directly in eBay -https://www.ebay.com/pages/help/stores/contextual/custom-store-categories.html. Once created in eBay, then the existing eBay store categories can be managed & refreshed by accessing them in an edit product page in the channel app.