Apple Power Macintosh 7600/200 Series - Manual (Page 109)

3 Unplug all the cables except the power cord from the computer.
Leave the power cord plugged in, or connect the power cord to your computer
and to an AC outlet if you have not already done so. (This helps protect the
computer from damage caused by electrostatic discharge.)
4 If the security bar is installed, remove it by removing the screw under the front panel and
pressing the center of the bar.
First, remove the screw.
Then, press the security bar near
its center to release it from the computer.
109 Installing PCI Expansion Cards and Additional Memory