how can i do that?

Not sure what your asking... if you want to remove the weaponfiles then open up dlc3.csv and comment them out (//), if you want to remove them from the box then just open up dlc3_code.gsc and change:

add_weapon("WEAPON_NAME", true);

to

add_weapon("WEAPON_NAME", false);

go to your zombiemode_weapons.gsc, if you dont have it in your mods folder then go to root folder, raw, maps, and drag that and dlc_code.gsc into your mods mapname folder.

In your zombiemode_weapons file look for

add_zombie_weapon

You may have to search for it twice to bring you to all the weapons, find the weapon you want, like for instance the kar98k, find the line that says

add_zombie_weapon( "zombie_kar98k", 						&"ZOMBIE_WEAPON_KAR98K_200", 				200,	"",				0);

Delete that line and the pack a punch line right under it, save it then open up dlc3_code.gsc, find include_weapon, again lets use the kar98k as an example, delete the 2 lines that say

include_weapon( "zombie_kar98k" );
	include_weapon( "zombie_kar98k_upgraded", false );

Now save it, and i dont know if this is neccessary but open up the weapons folder and look for zombie_kar98k, and kar98k_upgraded and delete both of them, now open up launcher select your map and make sure both the files are checked and then build the mod, now the gun should be gone from the map and you shouldnt see it in the box or as a wall weapon

can i comment the weapons out?
ex
// include_weapon( "zombie_kar98k" );

yes you can, i just like to delete it completely from the file