When you download an image created in DALL-E 2 it will have the colour swath watermark in the bottom right of the image, however according to DALL-E 2 terms this can be removed – which in many cases might be necessary for commercial work.
It should be fairly easy to remove the watermark in any app a with an object removal, clone stamp or content-aware fill tool, for example Photoshop. There is also a way to directly download the image without the watermark. On desktop, you can right click the image, choose 'Inspect' and then look for the windows.net URL. Copy this image link and you should find it doesn't contain the watermark. On mobile you can tap and hold the image on the generation page and click 'save image'.