Panorama Real Estate Inc., once a major force in the residential real estate business here, is slashing its staff, closing several offices and abandoning single-family home sales altogether, Lykes M. Boykin, president of the firm, confirmed yesterday.

Panorama's sales and support staff is being cut from about 360 persons to fewer than 20, and the firm is looking to get rid of its 11 area offices.

"We're totally changing the emphasis of our business by getting out of single-family home sales," Boykin said.

Two Panorama offices--in Potomac and the District--are being taken over by Coldwell, Banker, the real estate subsidiary of Sears, Roebuck & Co. Boykin said some 90 Panorama employes are joining Coldwell, Banker and that he is trying to place other employes in jobs.

Rumors of the Panorama pull-out had been circulating in the residential real estate industry for some time. Coldwell, Banker is expected to announce its plans for the two Panorama offices today.

E.A. Baker, president of Town & Country Properties Inc., one of the area's biggest residential real estate firms, said, "The significance of the Panorama news is that it is the first major company to do something this dramatic."

According to Baker, residential sales in the first four months of 1982 were off some 35 percent in Northern Virginia, about 30 percent in suburban Maryland and even more in the hard-hit District.

Panorama was "probably in the first six or seven" in sales among area real estate firms, Boykin said. But the firm, with its familiar yellow on maroon signs advertising houses for sale, fell victim to high interest rates and the sluggish real estate market, he said.

Emphasizing, "we are not going out of business," Boykin said Panorama plans to "consolidate" operations at its McLean headquarters.

He said the firm will now concentrate on selling commercial and industrial real estate, syndicating limited partnerships in real estate ventures and developing and selling condominiums.

"I'm looking for condominiums all around the country," he said, pointing out that Panorama is already in the condominium business in Louisville, Ky. Boykin said he is looking in New York City for buildings to convert to condominiums because that remains one of the strongest condo markets in the country.

Boykin acquired some operations from financially troubled Panorama of Greater Washington Inc. in 1976 and changed its name.

Real estate industry sources said Panorama was a middle-sized firm with high overhead and was vulnerable to the economic squeeze. Many firms of similar size are looking to merge or get out of the residential business, noted one real estate executive.

In contrast, he added, smaller real estate offices can survive because they have low overhead, while the big firms like Merrill Lynch Realty Inc.-Chris Coile Inc., Town & Country, and Coldwell, Banker have tremendous resources to tide them over.