Rejection

For comparison, this is what you're competing with in Stock inventory. 

https://stock.adobe.com/search?k=mashed+potatoes

Notice the well lit scenes, proper focus, pleasing presentation & camera distance from subject. 

Food photography is carefully staged to look delicious. It doesn't happen that way randomly. 

Uninteresting composition (square format usually is). Check your histogram for exposure issues going forward.

(& can i delete the NOT ACCEPTED files)

 

By @m_2666

I have thumbnails from before 7 years in my account for rejected assets. Those will remind me for ever about my failures. It's not an issue, it's only a thumbnail picture, and quite interesting to see your evolution as a stock contributor.

Food fotographie is a carefully orchestrated setting. It rarely works as snapshots. As @RALPH_L said, the asset is to dark, but there is also that disturbing background. And the colours do not seam to be right. There is probably too much saturation.

First of all, it is way too dark and the light brown area at the bottom is disturbing. 
No, you cannot delete the rejected thumbnails.