There was limitation of 2 level folder nesting allowed in env using below or equal to OBIEE 11.1.1.6.0.

This limitation has been enhanced in OBIEE 11.1.6.2 with excellent featueres. However in order to next the presentation folder’s, you should log in to OBIEE RPD and locate presentation layer. Then select presentation table the one you would wanting to see as parent folder.  Double click on corresponding presentation table to get into properties window containing multiple tabs. Go to Child Presentation tables tab in the presentation table to assign child presentation tables. So you assigns child presentation tables to give the appearance of nested folders in Answers and BI Composer. You can add multiple layers of nesting by following same method.

Here are graphical tips :

Structure the presentation tables/folder navigation  and click on RPD objects in sequential order similar to as shown in diagram below:

 

Make sure to Reload files and Metadata when you are working in online mode from presentation servers admin page and should notice in presentation catalog after successful service restart:

 

These folders appears as nested though they actually nested in terms of drill-down and qualified names of the objects shall remain the same. The presentation layer in admin tool does not show up as nested, though nesting appears only in Answers and BI Composer. This feature only works with presentation tables and not with presentation layer objects.