What your guinea pig is showing out is called conditioned behavior.
An experiment with chicken: Two cages of chickens had a similar food automatic device. The automat gave a grain of food when a chicken pecked a button next to the automat. In cage A the automat gave the prize every time the button was pecked. In cage B the automat, with no pattern, sometimes gave a prize and sometimes it did not. In both cages the chickens quickly learned to use the automatic to get the prize; the grain of food. That's conditioning with food.
The interesting part (considering your question) is what happened when the experiment had been going on for a length of time and then the automat was turned Off. In cage A the chickens gave up pecking the button quite soon, but in cage B the chickens kept on pecking the button a very long time after the automat was turned Off.
For un-conditioning your pet from its acquired behaviour the first thing to take care of is to never again offer him/her the prize right there in your kitchen when s/he comes running. (The word "wheet" is unfamiliar to me and also to those online dictionaries I searched.)
The next thing to do is to give the prize in an agreed upon (with your better half) spot somewhere in your home. A good place might be near the pet's cage. Whenever you want to give a treat to your pet, always take it to that spot. This way s/he will learn to wait there when hearing the sound of possible treats. I do this with my dogs. Any treat, like a leftover carrot when I prepare a dinner, I give in a certain spot outside kitchen. Our older dog likes a piece of carrot and goes to the right spot to wait when he hears me cutting carrots. I haven't trained any guinea pigs, but I see no reason why this might not work.
As with the chickens in cage B, the re-conditioning of your guinea pig will take time. The real hazard to the success is those accidental drops of treats that your pet has learned to wait. Accidental drops in kitchen may turn the task an impossible one.
Something to read:
Not related to this problem at hand, but otherwise rather interesting article about animal core instinct vs. conditioned behavior. Link to article. The core instinct eventually wins over conditioning.