He just has a mental condition so just ignore him.
What the hell is wrong with Macbeth?
Macbeth is unsure about going through with the plan to kill Duncan. Lady Macbeth is very good at manipulating him to get him to do what she wants him to. Lady Macbeth says he is a coward and uses this to manipulate him by verbally degrading him as someone who does not act like a man in order to get him to "man up". Lady Macbeth says that if she swore to kill her baby she would do it. They then discuss the murder plan in fuller detail.
Act four Warnings of Fate
Lady Macbeth gave the guards sedatives in their alcohol to make the guards pass out. Macbeth killed Duncan using a pair of daggers. Unfortunately, he forgot that he needed to frame the guards for the murder. Lady Macbeth then goes to the scene herself to put the daggers with the guards and smear the guards with blood. After this, Macbeth starts to regret murdering Duncan and Lady Macbeth is acting normal as if nothing happened. Lady Macbeth feels no guilt.
Act five Actions have Consequences
Macbeth was worried because Banquo, who is to father kings had become suspicious of Macbeth. Macbeth hired three people to kill Banquo and his son Fleabag (Fleance). Macbeth wanted Fleance dead because he is next in line for the throne. Banquo was killed but Fleance escaped. Macbeth then has hallucinations of the now deceased Banquo while at the dinner party. Lady Macbeth tells the guests that Macbeth just has a mental condition and to ignore his behavior.
Macbeth sees apparitions that warn him of his fate. The first apparition Macbeth sees is an armed head that says "beware Macduff". The second apparition is a bloody child that claims "none born of woman shall harm Macbeth". The final apparition is a crowned child holding a tree in his hand who states that "Macbeth shall not be vanquished until forest moves to Dunsinane". This causes Macbeth to feel safe and secure.