What TJ suggested is where the ammo itself is found. Unfortunately you will also need to remove any leveled lists that use it an containers too. I am not at a modding computer, so take this with a grain of salt.
There should be lists like LootAmmo32 and LootAmmo32Scrounger and those are placed inside of containers, such as AmmoBox32 and AmmoBox32Locked or they are used in leveled lists such as WithAmmo32Pistol or WithAmmoHuntingRifle.
THESE NAMES ARE SPECULATION.
I think I am close, but without it in front of me I can't give exact names.