Reset of Splash Math score can be done by deleting and then adding the player again. 
Splash Math needs at least one player to function. You will have to create a new player and then delete the existing player. 
Steps to add a player
- Click on the Profile button on the left bottom corner of the screen.
 - A Pop-up Screen will appear where maximum of 6 users can be setup.
 - Click on any of the empty/unused player boxes.
 - Type the player’s name.
 - Select the avatar.
 - Press ‘Done’ and you are good to go.
 
Steps to delete a player
- Click on the Profile button on the left bottom corner of the screen.
 - A Pop-up Screen will appear where maximum of 6 users can be setup.
 - Select the user you want to delete.
 - Click on Delete Profile button on the left bottom of the Pop-up.