remove over part

[Tropical5CF0]

how do I remove this green rectangle under the red grid line part in illustrator?

[Met1]

Can we assume selecting it and deleting doesn't work?

Is it grouped? Is it part of a clipping mask?

[SJRiegel]

Are you wanting to remove the part of the black line that is under the square area? 

You could use PathFinder > Minus Front or create a clipping mask. 

[Met1]

Ah, in that case you might need to convert the black to outlines first if it's a brush or a width widened stroke to get that crisp horizontal cut...

[Tropical5CF0]

yes of course I need to cut the black line of the green rectangle section

[Met1]

Glad I could help you...

[Tropical5CF0]

yes of course I need to cut the black line of the green rectangle section

[pixxxelschubser]

If you can't (or don't want to) outline your black object, use a clipping mask or an opacity mask instead.

[Jacob Bugge]

Tropical,

The urge to be silly has become irresistible, sorry.

You can also select the green rectangle and switch from Stroke to Fill (or just add any Fill if you wish to keep the green Stroke), then select the Fill in the Appearance panel and set the Opacity to 0 in the Transparency panel, then Group the path and the rectangle and tick Knockout Group (still in the Transparency panel).