Not sure if you can do this on the app or mobile browser, but it can be done on a PC / Desktop and use Chrome or Firefox as they work best with eBay.
On the Seller Hub, go to My eBay Selling >> Active Listing.
Under the title Quick Filters click on the tab Promoted Listings Standard - promoted.
This brings up all the items where Promotion has been added.
On the left click on Edit Promoted listing, then you can see where to deselect the blue toggle to show a clear toggle scroll down click on Apply.
Find the Seller Hub if you're not on it already here:
https://www.ebay.co.uk/sh/ovw
@cooltide67