Illustrate file was imported with option of creating composition & Retaining it's Layer Sizes. Double clicking on composition icon creating it's layers in the timeline. After that layers in the timeline were intentionally deleted to see the result in the composition. But the composition became blank after deleting it's layers in the time line.
Is there any way to delete layers without making composition blank?
AE does not store any persistent data of its own, only references to external files, so no, there is nothing left once you delete those references regardless whether you merely delete them from the timeline or the project window.
Thanks for the explanation.