I remember asking once, we don't we just shoot our surplus trash off into the sun and was told that by the cost of launching it outweighs the benefits. Fair!
But what about all of the old satellites and space stations? Why don't we just send a giant magnet around the earth once or twice and then slingshot all that space junk into the sun and thus giving all science fiction writers (when they return from their strike) a plot point they can no longer use in their film scripts?
Seriously though, without the cost of breaching the atmosphere, this seems really cheap to pull, why don't we do this? Why isn't this a standard thing?
To hit the sun, you'd need an object to cancel out all of the speed it has as part of orbiting with the earth around the sun, so that it could fall in. That 29.78km/s requires a lot of fuel to achieve, getting into orbit of earth only requires around 8km/s of delta-v.
So to go from an earth orbit to fall into the sun would require more than twice as much fuel as it took to get from the ground into that orbit in the first place.
If you want a more in depth dive, with more a focus on why shooting nuclear waste into space is a very bad idea: https://youtu.be/Us2Z-WC9rao