我们不需要这个怎么翻译

是We don't need it.
need既是情态动词也是实意动词，情态动词的否定是need not ＋动词原型，实意动词的否定是 don't/doesn't need＋名词、代词或to do sth。这里it是个代词，所以用need的实意动词的否定形式。

we don't need.
need not 后面跟动词。不必做某事

we don't need+名词
we need not +动+名