It is impossible to remove the knox bootloader and flash a non-knox bootloader.
It depends on you: do you care about warranty? If yes than use Towelroot because this wont trip knox (not complete 100% safe but most of the users reported it). I dont know if knox trips when you remove system apps/system files. You can live with knox. In my opinion the firmware is not bloated very much but ,again, it's your decision.
If you dont care about warranty you can use the good old way and flash recovery and flash a rootkit.