Dell OptiPlex 5055 Small Form Factor Owner's Manual page 16

4 To remove the PCIe expansion card:
a Pull the release latch to unlock the PCIe expansion card [1].
b Push the release tab [2] and lift the PCIe expansion card out of the computer [3].
NOTE: The release tab is at the base of the expansion card.
16 Disassembly and reassembly