Remove transparent pixels after rotating

Thanks for testing it, marc_3925 — that result actually makes sense in this case. Trim can only remove a strip that is transparent across the entire width or height of the canvas. After rotating, your image still touches all four edges (at the corners of the rotated image), so there is no fully transparent strip for Trim to cut away — that is why nothing visibly happens. The transparent triangles sit inside the rectangle, so the only ways to remove them are the two D Fosse mentioned: crop in past them, or fill them (for example, select a triangle and use Edit > Content-Aware Fill) if you want to keep the full canvas size.

Just use the crop tool, don’t overcomplicate this. Hold Shift to maintain proportions.

If, however, you need to keep those transparent areas, but fill them seamlessly with pixel content, it depends on what those edge areas look like.

Hi marc_3925,

You were close — you don't need the Ctrl-click for this one:

1. Choose Image > Trim.

2. In the Trim dialog, select Transparent pixels.

3. Make sure Top, Bottom, Left and Right are all checked under Trim Away, then click OK.

Photoshop will then crop the canvas to remove the transparent areas at the edges.

Official doc (see 'Trim transparent or background pixels'): https://helpx.adobe.com/photoshop/desktop/crop-resize-transform/resize-adjust-resolution/crop-and-straighten-images.html