I am emphasizing what Cosmas had stated.
Open World Editor -> Object Editor -> Units Tab -> Select any Hero unit;
Stats - Starting Agility: 0
Stats - Starting Intelligence: 0
Stats - Starting Strength: 0
NOTE:
Remember to hold SHIFT button + double-click the field first before input the values. This technique will allow you to bypass the default limits in Object Editor data, else, you can set a minimum of 1 value per stat.