“Home Improvement” has scored the equivalent of a one-punch knockout on CBS’ “South of Sunset,” with reports that the Paramount drama will be yanked after just one airing.CBS will apparently replace the show with the reality series “How’d They Do That?” in its 9 p.m. slot next Wednesday (the first night of the November Arbitron ratings sweeps), after a premiere in which “South” headed that direction, garnering a 6.1 rating, 9 share in Nielsen. That’s believed to be the lowest regular season, primetime series premiere share ever on one of the Big Three networks. The network confirmed that the show would be off next week but wouldn’t discuss scheduling plans beyond that. Starring former Eagle Glenn Frey and comic Aries Spears, the series entered the fall with a six-episode order. Lead-in “Hearts Afire” (7.9/12), meanwhile, didn’t fare a whole lot better, running fourth in its timeslot, as the revamped John Ritter-Markie Post comedy was blunted by a “Home Improvement” repeat at 8. “Hearts” producers Harry Thomason and Linda Bloodworth-Thomason had lobbied to get out of their originally scheduled Friday slot but may not have improved their prospects at 8 p.m. Wednesday — an hour where CBS has struggled for years. At the time the switch was made, the show’s order was reduced from 22 to 13 episodes. “Home Improvement” (24.4/36) exhibited a dazzling display of power at 9 p.m. — the Disney show’s second-best rating ever behind its Feb. 10 broadcast leading into ABC’s Michael Jackson-Oprah Winfrey interview. Lead-out “Grace Under Fire” (18.7/28) also scored its best rating yet. All three networks achieved 95% clearance or less Wednesday because of preemptions in Los Angeles, the U.S.’ second largest TV market, due to local fire coverage.