chain ring triple to double

Habany

hello Folks,
i own a KHS XCT565 bicycle with the following specs:
http://khsbicycles.com/bikes/2012-khs-models/xct-556/
i need to know whether can i replace my triple 22/33/44 chain ring with double 24/36 assuming the shifter replaced already.
do i need any kind of spacer in order to keep spacious between the small ring to the frame (rear triangle)
thanks

cooldad

Or just remove the big ring and use the limit screws to stop it changing too far.