Change background image in PHP

You won’t be able to delete the image per se, but using CSS you can hide the image. You should also make sure you fix the typo inside of your inline style it should read background-image: url(...).

For the varying styles, you can utilize media queries to hide at a certain point. I don’t recommend using !important but it will be the only way to override this inline style using CSS.

@media screen and (max-width: 576px){
  .myPost{
    background-image: none !important;
  }
}