If the delivery date is going to be any later than sometime this week, then I won't be needing the item anymore.
If it's going to be delivered later than this week, I will not be accepting the delivery anymore.
ご質問ありがとうございます。
① "If the delivery date is going to be any later than sometime this week,"＝「もし納品が今週以降になるなら」
"then I won't be needing the item anymore."＝「もうその商品は必要ありません。」
② "If it's going to be delivered later than this week,"＝「もしも配達が今週以降になるのなら」
"I will not be accepting the delivery anymore."＝「配達はもう受け取りません。」
ご参考までに。
If it will arrive later than that, I won't be needing the item anymore
If it will arrive later than that,
それ以上(到着が)遅れる場合は、
I won't be needing the item anymore
(商品は)もういりません
もう受け取るつもりはない、は直訳的に
I won't have the intention to take it anymore
とかになりますが、そういう表現はあまり聞いたことないですね。
もう要らない、送らなくていい（you don't need to send it to me anymore)などの表現の方が多く使われています。
ご参考になれば幸いです！
アメリカ合衆国 
