According to the WCAG guidelines decorative images should not have an alt-text but this is not possible

the webeditor uloads an image and fills in the alt-text and places the image in the content (or refers to it).
According to the wcag guidelines decorative images should not have an alt-text but this can not be undone since there is no way to alter the given alt-text.
The only option is to upload the image again, this time without alt.
This way we create a lot of duplicates in the media and create a not maintainable bulk of media.