First things first. You don’t want to cut your nutritional needs short. It’s miserable. But to answer the question as stated — there is no magical number of calories per day below which point you quit losing weight.
It would be great if that happened, because nobody would starve from lack of food.
But we’re not like that.
In fact, there is no starvation mode unless you are actually starving. And if you’re carrying around 6 months or a year’s supply of food as body fat, you’re not starving.
BUT. Do meet your nutritional needs each day.