Glenn Colerider       In his announcing days at WHKK, he was known only as Glenn Brooks, but today the name Glenn Colerider is known all over Northeastern Ohio for his many TV and radio commercials.       Glenn started at WHKK in 1951 and ran the gamut of staff announcing duties. In 1955, he took over the bookkeeping chores at the station and continued in this position until 1959 when he joined an advertising agency in Cleveland . During the 22 years that he was with the agency, he did free-lance TV and radio commercials and in 1982, he decided to devote himself to full-time free-lancing.       He and his wife, Jean, are very active in Cleveland area theaters. They both act and Glenn also directs. They reside in Brecksville and are proud of their three daughters and two grandchildren.