Dell OptiPlex Small Form Factor Plus 7010 Owner's Manual page 104

Steps
1. Remove the screw (6-32) that secures the front I/O bracket to the chassis.
2. Rotate and remove the front I/O-bracket from the chassis
3. Disconnect all the cables that are connected to the system board.
4. Remove the four (#6-32) screws that secure the system board to the chassis.
104 Removing and installing Field Replaceable Units (FRUs)