As part of its drive to slash costs, debt-laden Westwood One has sold its WYNY-FM radio station.The company announced yesterday that it has signed a definitive agreement to sell its New York country station for $ 50 million to Broadcasting Partners Inc. , which owns several radio stations around the country. The sale is subject to the regulatory approval of the Federal Communications Commission. One broadcast analyst dubbed the $ 50 million price “aggressive,” and said the price rewarded Westwood One for successfully changing the station’s personality and programming mix. Westwood One purchased WYNY for approximately $ 39 million in cash in 1988. The company said the sale of WYNY allows it to continue to reduce its financial leverage. Last August, it sold its other New York station, WNEW-AM, for $ 13.5 million in cash to Michael Bloomberg, the financial information marketer. It still owns KQLZ-FM in Los Angeles. Currently, the company has about $ 165 million in outstanding debt. Westwood chairman Norm J. Pattiz said the deal should help boost cash flow at the company, where losses dropped even further into the red in its third quarter ending last Sept. 30. A company spokeswoman said the company intends to keep concentrating on its core business, the three radio networks its owns — Mutual Broadcasting, NBC Radio and Westwood One. Wall Street seemed to like the move, pushing the stock up 13 cents to close yesterday at $ 2.63. Broadcasting Partners, which owns and operates radio stations in Chicago, Detroit, Charlotte and Dallas, said it intends to keep WYNY’s country format. The station ranks among the top 10 in the New York metropolitan area in the 25- 54 demographics, according to analysts.