At the top of any HubPages page, click on your username. A drop-down menu will appear. Select "my account". Once you're on "my account", you'll see a list of all the hubs that you have.
At the top of the page, you'll see another menu bar with "hubs" selected. Click on the "photos" button and you'll be taken to the list of all photos you have uploaded to HubPages and have used on your hubs.
Simply hover your mouse over an image and you'll see 3 options. One of those options is "remove from gallery". Select that option to delete unwanted photos. Hope this helped.