Write an article based on this "Open your document in Illustrator. Click Object. Select Artboards. Click Fit to Artwork Bounds."
Double-click the Illustrator project to open it. You'll need to have the project open in Illustrator in order to change the artboard size. It's a menu item that's either at the top of the Illustrator window (Windows) or at the top of the screen (Mac). Clicking it prompts a drop-down menu. This option is at the bottom of the drop-down menu. A pop-out menu will appear. It's in the pop-out menu. Doing so will resize your artboard to fit its art. If you have multiple artboards, each artboard will be resized.