This is how I do it in PS Elements:

Draw your rounded rectangle with the draw tool.
Simplify the layer
Select the shape with the Marquee tool (I use Magic Wand tool)
Go to EDIT/STROKE
Select OUTSIDE/CENTER/INSIDE for line location around the shape
Select width and color of line
Click OK
Use ESC key to exit Marquee tool
Click Marquee tool again and select inside the shape (the color you want deleted)
Click EDIT/DELETE

You should be left with a line around the shape.

When I use your DELETE method it only works if I choose the OUTSIDE line option. On the INSIDE line option it deleted everything including the outline and on the CENTER option is deletes half of the outline width. That is why I added the SELECT at the end in order to isolate just the color inside the new outline whether it is outside or inside.

In Photoshop Elements you can use the IMAGE/PERSPECTIVE menu item to get that kind of shape from a rounded rectangle shape. Drag a corner.

In WORD you can draw a rounded rectangle then right click on the shape and choose edit points. Drag a corner to move one side. It is tricky because you will have to drag a couple of corner points freehand to get it.