Hi, Vivkr,

I have two methods at least.

The first, define a layer mapping file that contains all the required layers. The layer not defined in the layer mapping file will not be streamed out. The step-by-step operation is shown below.
In CIW, choose File -> Export -> Stream... . Then the Virtuoso Stream Out window is poped up. Click User-Defined Data button, a new window is poped up. Fill the layer mapping file name in Layer Map Table. Click OK. At last, click OK in Vrituoso Stream Out window. A GDSII file is generated which doesn't contain the layer that you want to delete.

The second, this method is easy to use if you don't have layer mapping file. Before you stream out the GDSII file, change the property of the layer. The step-by-step operation is shown below.
In CIW, choose Tools -> Technology File Manager... Then Technology File Tool Box is poped up. Click Edit Layers... button, Layer Purpose Pair Editor is poped up. Select the layer that you want to delete. Click Edit.. button. A small window is poped up. Deselect Translate streamlayer and click OK. Then stream out GDSII file.

Good luck

Yawei