How to delete administrator password on aerobook

I created a password as administrator in my Aerobook laptop. I dont want to use a password anymore but when I entered in the Bios security area it only lets me change the password but not remove it (if I try to enter no digits or letters it says invalid code)
I need some help. Please anyone knows how to delete administrator password

First you need to enter a valid password, press enter, then you can leave the entry box blank and confirm twice.
Also, in some cases, resetting bios settings may help.

Thank you for your advise. I tried several times to leave the entry box blank and confirm twice but it says …error —invalid input range. I can only change the password but not remove it