If you don't have any admin-level accounts you'll need to reboot and go into the special boot menu to reset the password:
1. Connect a serial cable to one controller 1 and verify it was prompting for login prompt.
2. Power off both Power supplies
3. Power on one (or both Power supplies)
4. When Controller 1 says "Press Control C" to stop boot process (Or something like that.) then Press Control-C. This will take you to the "Loader-A" menu. (This is needed because you have to pause the bootup of this controller. Otherwise when you chose option 3 on Controller2, Controller 1 will be finished booting and controller 2 will hang at "Waiting for Giveback")
5. Now move your serial cable to the other Controller. (You have to do this quickly)
6. Wait until this controller says Press Control-C for Boot menu. -> then press Control-C
7. Then chose option 3 for "reset Password"
8. It will then think for a while and then give you an option to reset the password.
9. Then it wil finish booting this controller and prompt for login. Login with your new password.
The steps above are from this article:
https://community.netapp.com/t5/Data-ONTAP-Discussions/Reset-admin-Password-on-Clustered-ONTAP/td-p/125508
That was for ONTAP, but the basics are the same (i.e. you'll need to reset via the boot menu).
Good luck,
Chris