I can insert TOC for entire document.
I can insert TOC only for one chapter (aka heading 1) too.
How can I insert TOC for sub level (heading2, 3, …) ? When I try libreoffice insert TOC for chapter level 
Thanks
Please have a look at → Heading 3 not appearing in table of contents
(“Evaluate up to level…”).
Nope. Evaluate up to level permit TOC 1 to x but not x to 10
Please see my updated answer.
Please have a look at → Heading 3 not appearing in table of contents
(“Evaluate up to level…”).
EDIT 2013-01-17
I see! 
A possible workaround (only) for the final version
(the “TOC level 1 entry” would be recovered after an index update):
Tab Index/Table: Disable
☐ Protected against manual changes.
Remove the “TOC level 1 entry” manually (and save) …
… or select/highlight the “TOC level 1 entry”
Menu Insert → Section → 
Hide (and save).
Before
After
Sorry – having trouble upvoting your answer and getting it to stick! Site is experiencing some weird lag right now.