Scrape away as much of the putty as you can with a spoon.
Drip rubbing alcohol over the remaining putty with an eye dropper. Wait two to three minutes, then scrape the area again to remove more of the putty from the sofa fibers.
Spray the area with water-displacing spray if the rubbing alcohol didn't fully remove the putty. After two to three minutes have passed, wipe up the last bit of putty with a clean white rag.
Flush the cleaning solutions out of the sofa with cold water, then blot dry with a white towel.