How to Detect Rotor Disc Alignment or Warping

1st Method:
Remove brake caliper.
Hold the brake pad and rotate the rotor disk.
Observe the brake pad and bracket.
If brake pad moving on the bracket while rotating,
the rotor disk might be warped or not seated evenly on wheel hub.

2nd Method:
More works as the bracket need to be removed.
Find any size bolt and install it as above.
Adjust the bolt as close to rotor disk.
Observe the gap between bolt and rotor disk while rotating.
If the gap not evenly on all surface, check the wheel hub.
If the wheel hub is good, try to skim it and retest.

This is an example the wheel hub had hammered on some spot.

Grind it and retest.
Don't forget to check the rotor disk itself.
Maybe some pieces of metal fell in.

Good Luck!