Thank you Vijay, for your quick response. However, none of your suggestions worked. Later I found the solution on a Chinese site. I will recap it here for other users' reference (advanced).
- Windows Key + R. Open regedit.
- In regedit, find \HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Power\PowerSettings\238C9FA8-0AAD-41ED-83F4-97BE242C8F20\7bc4a2f9-d8fc-4469-b07b-33eb785aaca0
- Double click on "Attributes" on the right-side panel
- Change "1" to "2".
5: Windows Key+I > System > Power & sleep > Additional power settings to open Power options > Change Plan Settings > Advanced Power Settings
- Sleep --> Hybernate after (Set it to whatever you want).
- Apply the change.
Please note that on the editions of Windows 10 I've been using, the Hibernate option didn't appear until I changed the regedit entry.