First, drag the body upstairs to the bathroom. Slit the throat, groin, and wrists in the tub and drain as much blood as I can (first make sure the drain is unclogged). I'd then leave the body there and go clean and disinfect the kitchen. It'll take a while but I've got some serious disinfectants under the sink. Hopefully there isn't much blood on the walls, table, appliances, and ceiling. After that's done (which should take about 90 - 120 minutes), I'd go back to the body with... uh... I don't think I have a sharp enough knife in this house to saw through bone so hopefully our good knife can get through the joints; if not then I'm screwed. If you carefully rearrange the body parts, you can fit a 200lb body into two shopping bags. I'd probably have to use a third bag, like a Walmart bag, for the weapon I used to kill the guy and the other instruments I used like the sponge and towels from the kitchen and the knife I used to cut him up. I'd then re-clean my kitchen, this time focusing on removing the smell. I can get tips from the internet on how to do this.
I'd go out that night with the bags and deposit them at two different, distant dumpsters, no less than a mile from my house. I'd get the energy somehow or I'd take a chance and grab one of the buggies lying by my house. And the whole time I'd be hoping that neither my mom nor my sister comes home during this ordeal or the guy doesn't get reported missing until the next day or two (or ever, ideally).