You can leave the spindle attached or remove it from the knuckle and brake backing plate. Either way.
If you leave it in place, you can remove the knuckle, backing plate and spindle as a unit by detaching the tie rod end, taking off the knuckle seal on the inboard side of the knuckle and removing just the top kingpin.
Have some baling wire handy to suspend the knuckle unit in the vicinity so you don’t have to disconnect the brake line.
You can then pull out the axle to check its u-joint, and you can replace the king pin bearings.