bought a second hand mac is it possiblr to reset it ti factory settingd without previous owners lig in details

You can reset a second-hand Mac even if you don't have the previous owner's login details. Here's a simple step-by-step process:

1. Start by shutting down the Mac.
2. Turn it back on and immediately hold down the Command + R keys until you see the Apple logo. This will boot your Mac into Recovery Mode.
3. Once in Recovery Mode, select 'Disk Utility' and click 'Continue'.
4. Select your startup disk (typically named "Macintosh HD") and click the 'Erase' button. Make sure you choose 'APFS' as the format if it's available.
5. After erasing, go back to the Recovery Mode menu and select 'Reinstall macOS'. Follow the instructions to install a fresh operating system.

Keep in mind this process will erase everything on the Mac, including the previous owner's files and apps, so make sure you don't need anything on the Mac before proceeding.

Keep in mind recovery only works on mid-2011 and later Macs.