How Do I delete my hardrive

Hi
I am considering giving my computer to a nephew for xmas and buying another imac. I dont have much on it now. Can someone tell me some easy steps to wipe the computer clean and how do i reinstall the system. Do i just need the install discs
Many thanks

If someone can explain it in the most simple way that would be greatly appreciated
Happy Holidays to all

Do you have the install disks?

If you do, just put the first one in and a screen should pop up. Double click the install button. Then the computer will restart and take you to an install screen.

Select english as your language, continue. Accept the license agreement. Next screen it should have an options button at the bottom left. Click it.

Once you click options you will be given a list of choices. Make sure to click the "Erase and Install" option and then click next.

Continue on to finish the install and there you have it. A clean computer for your nephew.

many thanks

I really appreciate it Thanks again Im somewhat new to macs

No prob, glad I could help.