しつけーなっ！comes from "しつこにな”, which literally means "boy, you sure are insistent / boy, you don't give up, do you?" It is said when someone is bothering you with his or her incessant talk and you just want to be left alone. So it means "I don't want to talk to you any more - leave me alone."
いいかげんあきらis probablyいいかげんあきらめろよ, which means "please be reasonable and stop what you're doing"
Special thanks to Ryoko-san for helping to decipher the second sentence, which is only a partial sentence that I also could not understand.