If you select the zipper in the 2D or 3D window, the Context view displays the following Actions section.
Displays in a square information about the edges the zipper is connected to. If the zipper is connected to one edge, only that edge is displayed.
Hover over a square and a “-” icon is displayed. Click the “-” icon to disconnect the zipper from that edge. Do one of the following:
Zipper Width - Type in the desired width.
Change how much the zipper is zipped by either dragging the zipper image, or typing the percentage in Zipped.