Recovery of hacked account

Hello

My gmail account "***@***" was taken over by hackers officially since March 2018 but since January 2018 via my hacked mobile. I changed my mobile number and now cannot recover my account. Please advise how to do this or simply delete the account. I set up this account in May 2017 when I purchased my new Samsung S8 mobile. Thank you so much for your help and advice. The only different info is my mobile no. I can provide the original mobile number. Thank you.