There are three ways to say it: 1. 나는 청소해요. 2. 내가 청소해요. 3. 나 청소해요. (*) All can be said, but if you do not have any particular nuance to add, #3 is the common way to say it. 청소하다 is the verb for "clean", so you write it as one word. "요" makes it polite sounding, so you can just say 나 청소해 when speaking to a close friend.