kok leong Teo, here is what the manual says to do :"Before removing the hard drive or SSD, follow these steps:
1. Shut down the computer. If you are unsure whether the computer is off or in Hibernation, turn the computer on, and then shut it down through the operating system.
2. Disconnect all external devices connected to the computer.
3. Disconnect the power from the computer by first unplugging the power cord from the AC outlet
and then unplugging the AC adapter from the computer.
4. Remove the display panel.
5. Remove the base enclosure.
6. Disconnect the battery cable.
Remove the hard drive:
1. Disconnect the hard drive cable from the system board, and then remove the 4 screws
securing the hard drive to the top cover.
2. Remove the hard drive.
3. Remove the hard drive connector cable. Remove the 4 screws securing the hard drive bracket to the hard drive, and then remove the hard drive bracket.
4. Remove the hard drive.
Reverse these procedures to reassemble and install the hard drive.
Download the service and maintenance manual from here. It will give you all the details. Hope this helps, good luck.