According to the SmartImage API docs, there is a option to disable the upload of this component.

allowUpload="false"

Unfortunately, it is still possible. I tried to solve it, by –preventing the click event–. Nothing.

I solved it using a CSS workaround, that hides the file upload field. Don’t forget to specify the id in both snippets. Add this to your css to hide the upload field

/* Hide upload field */ 
#some-unique-id .x-form-item {
  display: none!important; 
}