I don't remember the administrator password and I want reboot and wipe the computer clean as if it was a brand new computer

To reboot means to power off and power back on. What you want is to restore to factory settings.

Did you create a Restore disk? If not, can you get into the Restore partition when you power on?

If they have a Hidden Partition, you can, or you will need the Discs.
Google your model and hidden partition and see what comes up. If you have 1 you can, if not you can't
Model # ?