OMG! LOL! At first when I read the question (before I put my glasses on) I thought it said how do I remove a foot from my wall.
Unfortunately, you will still need to wipe away some of the soot, which will spread it, but the paint will adhere better if you do that first. It is also less likely to retain the sooty smell if you wipe some of it away first. And you might need to use a product like Kilz latex stainblocker after you’ve wiped the soot (and spread it). This will seal the offending sooty color and smell. After the Kilz is dry, then re-paint over it with your regular wall color.
Check with the paint guys at Home Depot or Lowe’s if you need any help. They can give you a better explanation of how to apply it and how long it needs to dry.