  Push the release tab on the card-retention latch outward. Pull the release lever away from the PCIe x16 card to release the securing tab from the dent in the card. Then, ease the card up and out of its connector and remove it from the computer. Lift the PCIe x1 expansion card (if any) up and out of its connector and remove it from the computer. see p.11 [URL]  
I just got my TP Link WiFi card today but I have no idea how to remove the pcie bracites! Please help!
Dell Optiplex 3010 MT pcie bracket removal?