Keyboard shortcut to delete row in Numbers

I can add rows conveniently using Option+Shift+Up Arrow (insert above) or Option+Shift+Down Arrow(insert below).

Is there a keyboard shortcut to delete the current row?

By default, no, there's no shortcut.

You can create one yourself though:

1. Open System Preferences → Keyboard → Shortcuts → App Shortcuts.

2. Click the + button to add a new shortcut.

3. Set the Application to Numbers.app, and the Menu Title to Delete Row.

   

4. Set your keyboard shortcut and press Add.

As of at least Numbers 4.3.1, there is a menu item in the Table menu for deleting the current row (as well as one for deleting the current column), with keyboard shortcuts:

Delete Row: Shift+Command+X

Delete Column: Shift+Command+Y