There is a 3rd method already being implemented,[1] though it is enhanced by your second method. If no more satellites were put in orbit, eventually there would be no satellites (or space junk) in orbit.

[1] https://en.wikipedia.org/wiki/Orbital_decay

Unfortunately I don't think it's practical to wait thousands-millions of years for everything to decay

How about 150 years? Because due to orbital decay, that is about how long it would take for everything to fall out of orbit. If there is a Kessler Syndrome, depending on its effect at higher orbits, it might take a few hundred more years, but definitely definitely not billions of years.

How on earth would a leaky Soviet reactor create orbital debris?

Commenter is probably referring to this incident[1] where a sodium-cooled nuclear reactor on a Soviet satellite ended up spraying a bunch of small beads of sodium into Earth orbit. The number and density of the beads makes them a long-lived hazard.

[1] - https://en.wikipedia.org/wiki/Kosmos_954

There's a few dozen nuclear powered RORSATS. When their start leaking (due to micrometeorite strikes or just wear & tear), they leak out globs of coolant that coagulate together. Each satellite has a few hundred points of coolant, which can make a LOT of 1cm across globs (or larger globs, or droplets that are too small to detect). I don't have a paper handy, but IIRC these droplets were the #1 source of space junk up until the 2007 antisatellite weapon test

e: Paper here, https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.27...

Thanks, I’ll read it.

I think you mean seppuku, not sudoku. :)

I said the said thing at first but learned it's an online meme :)