If you delete a selection on a Background layer or a layer that uses the Lock Transparency option, the selected area is replaced with the background color or checkerboard background pattern.
Choose Edit > Delete to remove the selection. (If you delete a selection by mistake, you can choose Edit > Undo to get it back.)
Press the Backspace or Delete key to remove the selection.
Choose Edit > Cut to cut the selection to the Clipboard. You can then paste it elsewhere.