Functions the same way as Surrender, but involves both teams. If greater than 60% of the remaining players vote to Disband, then the game ends and is neither a win or loss.
Disbanding should be available from the start of the game and it should give IP and EXP based on the game time. Before 10 minutes it should only give a token reward of 8 IP and 5 EXP, but as it approaches 50 minutes it scales up to being 75% as much IP and EXP as a loss on that maptype.
The purpose of Disbanding would be to allow games that experience leavers (esp. earlygame), bugs, or anything else that would unfairly imbalance the game to call it neither a win nor loss. Providing a small IP and EXP reward encourages public teams to disband in said situations.
Note: This idea is touched on by this thread and has been mentioned elsewhere, but this particular feature could use some emphasis and discussion for the developers.