Destroying clan halls ?

[Quellease]

Can I destroy other clan halls when I build the grandest hall ? 

And does halls have an effect on research costs ?

[Ronin_Warder]

9 minutes ago, Quellease said:

Can I destroy other clan halls when I build the grandest hall ? 

And does halls have an effect on research costs ?

Nope, you have to keep them Tenno. 

Edited July 27, 2016 by Ronin_Warder

[Honorbridge]

To have a grandest hall, you must have one of every other kind of hall.  If you want to delete one of the lower tier halls (as part of a re-design for example) you must delete every larger hall first.

Halls do not affect research costs, only Barracks do - because barracks are the method by which you increase clan tier (Ghost to Shadow, etc.).  Your clan tier is the determining factor of research costs.