How to Delete a User Account in Mac OS X Snow Leopard
After you set up a user account on your Mac, your aren’t stuck with it forever. If for any reason you want to wipe out an account from the face of the Earth, Snow Leopard makes it easy. To delete an account, follow these steps:
Click System Preferences and then choose Accounts.
The Accounts Pane opens.
Click the account that you want to delete in the Accounts list.
Although you should make sure you have the correct user account selected, you do have the option of aborting the action if you don’t want to follow through with the deletion.
Click the Delete User button (marked with a minus sign).
Mac OS X displays the confirmation sheet.
Choose what to do with the deleted account's Home folder.
Note that the contents of the user’s Home folder can be saved in a disk image in the Deleted Users folder (just in case you need to retrieve something). Alternatively, you can choose to leave the deleted user’s home folder as is, without removing it.
If you’re absolutely sure you won’t need the Home folder, click the Delete the Home Folder option (which doesn’t save anything in the Deleted Users folder). You regain all the hard drive space that was being occupied by the contents of the deleted user’s home folder.
This verifies the delete action and deletes the account.