Example with a context (YouTube link):
I drove slowly back to the office. The telephone was ringing when I arrived at the office. I went in quickly and answered it. "Samuel speaking." "Listen, Samuel," replied a voice. "Forget about Elaine Garfield. We hurt you a little in her apartment. If you don't forget all about Elaine Garfield, we'll hurt you a lot more."
I'm not exactly sure how I should understand all—as a pronoun or an adverb? It seems as though it can equally be understood both ways. For example, if we assume that all is a pronoun, then semantically the sentence will mean something like this: if you don't forget everything that you know about her, we'll hurt you a lot more. On the other hand, if we think of all as an adverb, we'll get the following: if you don't completely forget about her, we'll hurt you a lot more. The two meanings are quite different. Please, help me solve this little, weird grammar conundrum of mine.
Best Answer
I am not a grammarian, though I am a native speaker. The meaning in this context is, "Forget you even knew her." That is, to never see her or attempt to communicate with her again, as you will be hurt badly if you do. I know of a real-life event that may be related in context. A young man was dating a criminal's girlfriend. Others in the criminal network told him to stay away or he would be in trouble. After going out with her again, he found his very nice car riddled with 30+ bullet holes. I hope this example gives you a sense of how serious this warning can be in certain situations. I hope this context helps you to answer your question.