The answer is different if sending for print or using it as a web image. I shall assume that talking about buttons you mean for a web image. Rename the background layer to something other than Background. Delete the area you do not want. Select File>Save for Web and Save as GIF
Give your photos a professional finish with sharpening in Photoshop. Learn to enhance details, create contrast, and prepare your images for print, web, and social media.
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