Okay the math is obviously wrong, and it's not even answering the question.
The question was, how much force. If punting the kid involves a kick, let's say the foot makes contact with the kid for about 25 cm. Then the force required over this distance is on average 45 GN.
This is equivalent to the child experiencing roughly 180,000,000 G
Thats inefficient, you dont need to cancel the angular momentum as there was no time limit on how long it takes rhe child to enter the sun and there also was not a specified required trajectory. The child can just spiral into the sun
I don't think you can achieve a spiral orbit in an area with so little friction, mostly devoid of dust and gas, else the earth would be on one of those too...
Surely they're not so mad that they need to kick their child into the sun. I'm sure a low solar orbit would suffice.
"Then you'll be fired."
"Fine!"
"Out of a canon into the sun."