I tried using a site icon/logo on the website I am developing (MaritimeImages.net) but I don’t like the look and I know want to revert back to the text I entered in the Customizer for my site title.
When I delete the icon I uploaded I get an error message in the field “invalid value” and the icon is still present.
I hope you are well today and thank you for your question.
This is a known issue which will be resolved in the future version of theme.
In the meanwhile you can try resolving this by using the custom child theme of Shapely theme shared in the following topic that contains some custom code.