The doctor has just witnessed Lady Macbeth at the height of her madness. He is disturbed by it, and he asks the gentlewoman to "look after" her mistress, who, he thinks, needs the help of God more than his own. Because Lady Macbeth is so unwell, the "means of annoyance" should be removed.

The key word here is "means." It's tempting to translate this into modern English as something like "take away anything that might be upsetting or annoying her," but that's not quite accurate. In this sense, the "means of annoyance" are "things with which harm or injury could be caused." So, while the doctor certainly does want the gentlewoman to try and calm down Lady Macbeth and make her comfortable, he is here quite specifically asking her to clear the room of anything that might be used as a weapon by Lady Macbeth, to harm herself. Evidently, then, the doctor thinks that Lady Macbeth's state of insanity might turn towards the suicidal. Given the way she has behaved, if she has access to a weapon, she might even kill herself with it inadvertently, thinking it to be something else. So, the doctor is asking the gentlewoman, who is really Lady Macbeth's maid, to take away any sharp or dangerous objects.