Wiping and Reloading Old Intel Macs
1) Restart PC, and hold CMD + R to enter Recovery Mode.
2) Enter Disk Utility > Select Primary Drive Partition > Erase > Rename, select macOS Extended, Journaled > Erase
3) Exit Disk Utility
4) Select “Reinstall macOS ____”
5) If not given the option to reinstall most up to date macOS or says “Cannot contact servers”, restart PC and let it enter Internet Recovery to reinstall OS X
6) Once OS X is installed, you need to get the base OS installers from here and create bootable media to add the installer to the Applications folder and update from there.
7) For finding the installers
a. https://support.apple.com/en-us/102662
8) Directions to create bootable media with the installer