erase hard drive and reinstall macOS?

Hi whateverles! Apple has a support article just for this case. Check here:

What to do before you sell, give away, or trade in your Mac

Hope it helps!

-Geotrax

Clickhereand follow the instructions. If the computer originally shipped with Mac OS X 10.6.8 or earlier, when you reach step 6, insert a compatible Mac OS X install DVD, restart with the C or Option key held down, use the Disk Utility to erase the internal drive, and install a fresh OS.

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