Removing Product Category 'Image Unavailable' Icon

[Hawker]

When I view a list of products, I see the product category name displayed at the top of the page. Underneath it is an 'Image Unavailable' icon.

When I check at the Product categories>Image page, there is no image associated with that product category.

How do I stop the 'Product image unavailable' icon appearing underneath the product category name at the storefront's 'Products' page?
Thanks in advance for your assistance.