Dell OptiPlex 160L - Manual (Page 6)

4. Remove the two screws that secure the I/O panel to the computer.
5. Remove the I/O panel and disconnect the sound/USB cable from the I/O panel.
1 side hinges (3) 4 release lever
2 front panel 5 middle tab
3 top tab 6 bottom tab
1 screws (2)
2 I/O panel
3 sound/USB cable
4 tie wrap cord