Thanks for writing. You are not able to delete rejected files. Those remain in your account as a reference for previously uploaded content.
Can I resubmit an image, one of the rejected images, I made a mistake and used the wrong export preset in Lightroom and would like to resubmit it?
I want to delete rejects. There is no point at all in leaving them as reference. I do that myself. I have folders for previously submitted images. I want them gone. Make it possible. Also on images under the reminder tab. I will not be able to go back in time and get a model release for a stranger in another country.