Is there a way to remove the Cassador sound that you hear when you come near them, it is rely annoying and useless.

You could possibly replace the soundFX file with a dummy silent file so you don't hear it ever again but that would affect ALL poison attacks so it's a bit of a kludge. I don't know what triggers that effect exactly (the poison sound just for walking near them right?) but I agree it is very annoying. There are a few scripts that call that file but I'm unsure what effect good or bad altering any of them would have on this behavior. You could try commenting them out I suppose as an experiment if you want in a test esp file. If it causes Bad Things™ to happen just delete the test mod file.

In any case, the specific sound file you're looking for is FXPoisonStinger - find a dummy silent file and/or rename the FXPoisonSting file you can extract from the sound BSA as it appears to be such a placeholder and place as an override in your sounds directory under Data Files. Make sure you're using some form of Archive Invalidation if you try this.

Off Topic -> Are you the Ceano from STALKER modding by chance? Just curious.

Thanks will replace the sound file with a silent one.

Off Topic - > yes that's me

There is a silent .wav already in the game:

fx\npc\bighorner\breathe\npc_bighorner_breathe_07_silence.wav

I didn't like Lily's breathing sounds, she sounded like she had smoked way too much, so I reassigned the NPCSuperMutantBreathIn and ..BreathOut to that .wav in a Mod. Reassign the sound in the GECK in Audio->Sound, find the name of the sound you want to reassign. That way you don't have to have a separate file in the Data folder.

Are you talking about the wing flapping sound? That's the NPCCazadoreIdleLP sound. It's not very loud in my game because I never get that close to them, I always shoot them with a long range weapon.

Or are you talking about the sting/attack sound? There's four of those.