Deleting information from computer

How do I go about wiping information from a computer permanently? I am giving a friend my old computer but want to delete any information relating to me. Thanks

Firstly delete all the files and empty the recycle bins. Then run to ensure that the deleted files are not recoverable.

if u have a Mac and it has OS X ,

u can do whats called a low level format that is just a standard erase using disk utilty

or the more secure version is called secure erase its like writing zeros ,

"
Usually when you erase a disk or volume, Disk Utility only erases the information used to access the files on the disk, not the actual files. Because of this, the erased files can be recovered.
If you want to erase the files so that they cannot be recovered, you can select security options to write zeros over the disk space. To make it more difficult to recover the files on the disk, you can specify doing this once, seven times, or 35 times. If you have a large disk, overwriting the free space several times can take a long time."
If you select your startup disk, the buttons are dimmed because you can't erase your startup disk. To erase your computer's startup disk, you must start up from another disk. You can use your Mac OS X Install disc or the Software Restore disc that came with your computer.



im sure a PC or windows system has the same info or instructions to do same




u can also get third party utiliities to do the same job

If it is a pc and your going to format and reinstall software just take note of the drivers (network, sound etc) because sometimes they aren't picked up on the reinstall and its a bummer if you don't have the drivers disc or a note of them.