Android Reset Directions
The easy way:
Settings > SDCard > Format
Settings > Privacy > Factory Reset
The hard way:
Do a hard reset and format your phones. You will have to re-download your apps and settings.
1. HOLD power button and shut down the phone.
2. Hold HOME and RED POWER down for 25 seconds until you see a triangle with an exclamation mark in it. Keep holding it down even though the G1 logo shows up.
3. Now you can do 4 things.
Home+Back reboot system now (Soft Reboot)
Alt+L Toggle log text display (Toggles between the exclamation and menu options)
Alt+S apply sdcard:update.zip
Alt+W Wipe data/factory reset (Out of Box reset need to re-register.)