"Clean the kitchen."
Translation:E hoʻomaʻemaʻe ʻoe i ka lumi kuke.
Either of these is fine: "E hoʻomaʻemaʻe ʻoe i ka lumi kuke" or "E hoʻomaʻemaʻe i ka lumi kuke", where the ʻoe is understood. The "i" is an object marker. In this case it lets you know that what you are supposed to clean is the kitchen. Without the "i", ka lumi kuke is the subject of the sentence, instead of the object. "E hoʻomaʻemaʻe ka lumi kuke" reads like "The kitchen should clean (something)."
That said, in the speech of native speakers the "i" tends to get blended into the "e" at the end of "hoʻomaʻemaʻe", so it can often sound like "E hoʻomaʻemaʻe ka lumi kuke."