According to the following Acer forum post, you need to press the Del key. Try pressing it several time after you turn on the laptop. If you press it too much, the laptop will make a beeping sound which basically means it ignores anymore presses. If you see Windows booting up then you need to try again. Instead of logging into Windows simply shutdown (not reboot), then turn on the laptop and try pressing the Del key again.
According to the following Acer forum post, you need to press the Del key. Try pressing it several time after you turn on the laptop. If you press it too much, the laptop will make a beeping sound which basically means it ignores anymore presses. If you see Windows booting up then you need to try again. Instead of logging into Windows simply shutdown (not reboot), then turn on the laptop and try pressing the Del key again.