There’s only one rule that you simply must remember – BE NICE.
No gloating, no settling of scores, no telling the boss what you really think. No matter how much you want to, and no matter why you are leaving. It’s absolutely not worth it. Retail is a small world and people move around a lot. You never know who might ask who for an unofficial reference sometime in the future. You could lose out on an absolutely brilliant job and never even know that you were considered for it.
Think about it. Think before you act. A sensible, straightforwardly worded, unemotional resignation letter is required along with a sincere offer to work out your notice period.
Whatever your circumstances act as if you might one day want to come back. On a rainy day, you just might.
End of story.