There are numerous methods for making the transition from closed hold to open position in East Coast Swing. The most rudimentary is the Throwout.
It the simplest of terms, a Throwout is a type of left-turning Basic where the man releases the lady to open facing position. The left turning action combined with the "sending" of the lady from the man's left toward his right side, lend a Cross-Body Lead type of feeling to the Throwout.
The Throwout begins in promenade position following the rock step of the previous figure. The couple does not return to closed position, but remains in promenade as they dance the first chasse (1a2). During this chasse, the man leads the lady forward toward his left side while turning to the left. The lady can dance either a forward chasse or 3 passing runs, turning 1/2 to her left toward the end of the chasse. At the completion, the man releases his hand from the lady's back, and the lady releases her hand from his shoulder, to end in open facing position.
From there, they continue to dance as they would an open basic, the second chasse (3a4), followed by a rock step in open position (1,2). Due to her momentuum, the lady's second chasse will be side & slightly back.
A Simpler Approach
A easier method for beginners to transition from closed hold to open position is one where the man simply releases his right hand from the lady's back while dancing a non-turning Closed Basic, with both man and lady taking the second chasse to side & slightly back to end in open facing position. This is a good teaching tool for beginners, and can be used as a "stepping stone" on the way to learning the normal method as described in the man's and lady's charts.