If it’s the button I’m think of, it’s red (alongside the Search box after clicking Start).
I don’t use it but I think it was Hibernate. I say was (past tense) because I’ve changed it to Shut Down the computer. If you want to do the same, go to the Windows Orb (Start), type cmd and press Enter. Now type POWERCFG.CPL ,1 (the capitals are for clarity only) and press Enter.
Expand ‘Power buttons and lid’. Alongside both ‘Power button action’ and ‘Start menu power button’, click the blue wording dropdown menu (2 of them for laptops) and select Shut Down. In future, to shut down just click the Windows Orb (Start) then the power (red) button.
Any changes that you make can be reversed by clicking ‘Restore plan defaults‘. The changes are for the plan currently in use but it can be set on all plans in the event of you changing to a different one.