HP Compaq Pro 4300 All-in-One Hardware Reference Manual page 17

8.
To remove the memory access panel, press down on the tab on the inside edge of the panel (1)
and slide the panel off the computer (2).
Figure 2-5
Removing the Memory Access Panel
9. Pull upward on the raised tab on the memory cover and lift the cover off the computer.
Figure 2-6
Removing the Memory Cover
Removing and Installing Memory
11