I used the selection tool to drag part of one image onto another image in a new layer. That layer has a "padding" (not sure what else to call it) of about 75 transparent pixels around the image. I'm wondering if there's a way to remove the transparent pixels for that layer alone similar to the way one can use Image->Trim on the entire image. The purpose for doing this is so I can make an image sprite with each icon on a layer of the same size. Thank you so much!
The transparency is there because of a lack of painted pixels, so in this case you would not be "removing" the transparency, but rather filling in those areas.
If you place a new layer under the layer in question, and fill it with the appropriate color, and then merge the 2 layers, you will have a layer that extends to the edges of the canvas.