You cant remove the balls or the guns but you can stop the balls appearing by setting ball_life to 0.
Don't know if this is what youre trying to do, infact im pretty sure its not, but there it is anyway.
The other option, thinking about it, is to make a map which requires you to expend 10 balls in order to begin playing. Perhaps, for example, to escape from a room by shooting 10 buttons? Although im not sure this is the most suitable idea for DP
