@svanya
what the article says about dropping the 3rd, 6th, and 7th
The only thing that makes a scale/mode minor or major is the 3rd. The one we call natural minor or aeolian has minor 6th and 7th as well. There are other minor modes with less or more minor intervals
An easy way to think of the classic modes for me is the white keys on the keyboard, like @seb-harmonik.ar is hinting at. These are the start tones, modes and intervals (minor intervals denoted by lower case except 4rth and 5th on the account of musical convention)
C -> Ionian: I II III IV V VI VII (major)
D -> Dorian: I II iii IV V VI vii (minor)
E -> Phrygian: I ii iii IV V vi vii (minor)
F -> Lydian: I II III IV# V VI VII (major)
G -> Mixolydian: I II III IV V VI vii (major)
A -> Aeolian: I II iii IV V vi vii (minor)
B -> Locrian: I ii ii IV Vb vi vii (minor)
For each of the majors, they have a "parallel" minor which you could think of as a "90 degree shift" in the "no blacks allowed" chromatic circle - i.e.: 3 semitones down. Ionian becomes Aolian. Lydian becomes Dorian. Mixolydian becomes Phrygian.
HOWEVER, there are tons of modes/scales not accounted for here, a lot of which you can't play on white keys only. And there is no single major-to-minor transformative rule besides these:
1: Flattening the 3rd will effectively turn a major scale/mode into minor
2: A major scale will have a parallel minor scale 3 semitones below it IF AND ONLY IF the major scale has a major 6th in it