I can't access my gmail account

Hello,
my name is hannatu danladi. i registered an gmail account with this user name ***@*** early september this year but couldn't complete the process of the phone no verification. i went ahead to use the email to apply for job . now the company has sent me a link to the email to fill a form but i can't access the gmail again. i have tried to re-registered but the same user name was not accepted. please how do i delete the former and make a fresh registeration