To dream that you commit suicide represents self-imposed failure. It may also represent a desire to escape from a waking life situation. You may also have intense guilt, regret, or feelings of hopelessness in some area of your life. You may feel like surrendering to your problems or giving up fighting. Feelings about self-defeat, dropping out, or giving up.
To dream of someone else committing suicide represents an aspect of your personality that self-defeating or choosing to fail. It may also reflect your feelings about a person who has changed in ways you don't like. You may feel they are a "loser" or a "failure."
If you are actually thinking about committing suicide the dream may be a sign that you need to speak to someone about your problems.
Example: A student dreamed of searching his school for a person who was suicidal. In real life he was were doing very poorly in school and was considering dropping out.
Example 2: A woman dreamed of her old high school sweetheart committing suicide. In real life she had gotten back in touch with him, but felt that he had ruined his life.
Example 3: An elderly man dreamed of his recently deceased wife urging him to kill himself. In waking life he was considering suicide so he didn't have to live the rest of his life alone.