Do I need to send a non-renewal letter at the end of my employment contract?

Dear Advisor,

Good day!

I just wanted to seek your advice about my situation.

My labour contract in my company will be finished on December 14 as well as my Emirates ID and I am planning not to renew if I will be confirmed with the new company I'm applying for.

So I wanted to know if I need to submit to my company now a resignation letter or non-renewal letter and kindly explain to me why?

Thank you in advance.