Demolition crews using two cranes finished their work Friday dismantling the 275-foot Astrotower, reducing it to 92 feet, Department of Buildings spokeswoman Kelly Magee said.
Work resumed early Saturday, she said.
It was unclear how much more of the tower would be removed.
The noticeable swaying of the nearly half-century-old observation tower, which hasn't carried passengers for years, led to a shutdown Tuesday of a two-block section of the surrounding Luna Park amusement park.
The area includes the iconic Wonder Wheel and Cyclone roller coaster and the boardwalk.
Those closures remained in effect through most of the busy Fourth of July holiday but were lifted Friday afternoon, much to the relief of merchants and ride operators who had worked for months to restore Coney Island from damage caused by Superstorm Sandy in late October.
Luna Park spokesman Tom Basgil said he didn't know whether the tower would be removed or restored.