Cannot delete the logo image

First, please try uploading a different image to overwrite the current one and check if it gets replaced.
If it can be replaced, please check if you can delete the new image.

Next, please check if PHP is running in safe mode on your current server.
If it is running in safe mode, please refer to this article for countermeasures.
Also, we kindly request that you keep safe mode turned OFF.

Also, there may be an impact from the WAF (Web Application Firewall) in your server settings.
Please temporarily turn OFF the WAF before changing any theme option settings.
After changing the settings, please turn the WAF back ON.

For details about WAF settings, please check the information provided by your hosting provider or server administrator.