You always need starting points for any occupied player slot (Be it computer or user).
If you want custom starting points, there is nothing easier than placing Starting Location "unit" for each player. So you can have up to 14 starting points.
Starting points are the point where the player camera will be at the begginning of the map.
If you wanna use another one just move.
It's not town hall, however there is a trigger under Melee which will spawn town hall in Starting Location, so all you need to do is remove that action from map initialization trigger.(Starting location is the town hall?) No?
- Unit - Create 1 Unit for Player at Point facing Angle degrees