As I recall, Cox was an independent prosecutor. Bork replace the person who refused to fire Cox. Leon was a district judge, he didn't replace anyone but was a political pick by the democrats to jail the Republican administration. He succeeded.
..there anything that you think the President CAN'T do?
There are limits and the constitution prescribes the impeachment process. Nixon was never impeached. There was no 8-0. Leon accomplished it all. To this day Liddy views him as a complete rat!
Richardson, one of the few people in the administration that had a spine, refused, and then resigned. Dpty. AG Ruckelshaus was told to fire Cox. He refused, too, and also resigned. Ah, but then we have Solicitor General Bork, who was willing to blindly follow orders. "Fire Cox? You betcha Mr. President!"
Nixon found all of this investigation very annoying, and announced that he was going to abolish the office of the special prosecutor. Although a nice try, Nixon was later forced to name another special prosecutor, and ABA President Leon Jaworski was named.
And don't forget, the only reason that Nixon wasn't indicted himself along with Liddy is that Jaworski told the grand jury that in his legal opinion a sitting President could not be indicted. Nixon was named an un-indicted co-conspirator.
It's worth noting, too, that Nixon surely would have been impeached had he not resigned. He spared himself *some* embarrassment in the whole mess. But not much.