As per title, can't seem to find the KB shortcut anywhere, and it's something I frequently do.
(Windows, Project 2007)
You need to select the entire task first, instead of just being in a single cell:
There is a useful cheat sheet available on shortcutworld.
Delete entire row: Ctrl+"keypad minus key"
(as stated already, but not delete)
Note adding a task is ctrl+"keypad plus key" or just Insert