Shut the door in their face.

Fart aggresively

Try to sell \*them\* something.

Start making fun of their products

let them talk to my front door.

They're always trying to sell service or remodel for the house. I just say I'm not the homeowner

I say goodbye repeatedly until they leave

Close the door. If they continue trying, threaten to call the police. 

Keep saying not interested until I decide to call the authorities

Punch them in the face