6 minths baby pulls hair when gets fussy. Is ut normal? How can I stop that bad habit

Don't fret! If this is all, i'd like to reassure you. Since babies lack speech - they talk in gestures. This is an excellent icon of irritation. In english we even say "i could've pulled my hair out - i was so upset". Sympathetically say "oh my, you do feel upset!" and offer a distraction for baby to grasp - a toy or fruit bit and say "maybe this will help". It's not likely to be a habit. Here, have a grape.
NOT TO WORRY.. This is normal behavior. We can't label this as a bad habit... Considering her age. You don't have to worry. If possible, keep her hair short, put mittens/baby gloves on, so that she can't pull hair badly.