Please find below some community article which could act as some help to you,
//I have lost the password and I need to reset the admin password on CQ 5.5 or later.
//AEM 6 SP2 - Reset Administrator Password to admin offline
1) Stop AEM 6 instance
2) Place the package reset_admin_pass_to_admin.zip in <AEM_Home>/crx-quickstart/install (create it, if there isn't one)
3) Start AEM 6 instance
4) Package should have gotten installed as shown below. It contains /home/users/a/admin/.content.xml with rep:password set to text admin encrypted
5) Login as admin/admin
I hope this would help you.
Thanks and Regards