Based on the use of the expression in Palestinian Arabic, I'm guessing it means "I don't need you" or "I can do without you" or something of the sort. It might be slightly different based on context (for example, I don't need such behaviour, or I don't need that thing...etc.).
I am not sure if it is the same (correct me please if am wrong) but in english good riddance means you are happy that someone is gone and you actually wanted him gone all along while بالناقص is said when you are internally frustrated because someone's gone but at the same time you want to show indifference to the outside.
Same thing in Egypt, بناقص من instead of بالناقص and the meaning is: it’s better not to have, it’s not worth the trouble.
The interesting thing about the Egyptian usage is that من isn’t followed directly by a noun, but first a pronoun then the noun is refers to. For example:
بناقص منها الشغلانة دي ما دام مفيش وراها مكسب
بناقص منهم الصحاب اللي زي قِلِّتهم
I don’t remember hearing it used directly with a person بناقص منك but we can say بناقص منها معرفتك، بناقص منها مساعدتك I’d rather not know you, I’d rather not receive help from you.