Zig Zag Effect issue

Hello , I haven an issue with a zig zag tool.

I have a pattern with lines with zig zag effect.

I would like to delete all outside of this square.

I select all and do use Shape Builder tool to do it.

It removes the lines but it also apply the effect to the remaining lines so they 

look now how I dont want  them to looks like.

How to jjust remove outside line and keep theire shape ?

thank you