There's this little flap hanging and I would like to replace it or if it's useless I would just remove it. I don't really know the purpose of it or why it's hanging like this or what it's called.

 

They are air guides or air deflectors. They redirect air from going to the tire as the tire is a high turbulent zone, it provides better aero dynamics lowering drag coefficient.

not sure rear part number but front right and left

https://www.discountoeminfinitiparts...k60a-80350.htm

https://www.discountoeminfinitiparts...k60a-80348.htm

 

so it is supposed to be hanging out like that, just not as much...

 

From what I can tell/see in the pic it looks perfectly fine and normal.

unless its noticeable damaged/ripped or missing the pop clips then it should be fine.

it sits in front of the wheel blocking air that is under the vehicle on the sides from going to the wheel, instead it redirects the air to the center of the undercarriage.

 

it just looks like it's supposed to be up in that little slot

 

compare it to the other side. You have 1 in front of each wheel. Although the front are a little different.

does it look torn?

 

yea only the left side was hanging like this. i don't think they were torn