Reset AIX root password without shutting down the system

Hi All,
I'm stuck in a severe problem here , Someone have changed the root password
and he cannot remember it and there is no other user privileged user on the system , But I do have access to a non privileged user.
On the top of the system an application which requires a theoretical 24/365 availability and that application requires graceful shutdown and it's running under another user ID which the password is also lost bad luck we always do su to that to stop the application ( true laziness ) we (the unix admins guys ) cannot risk to forcelly shutdown the application .

Now I want to at least stop the application gracefully if someone have an idea to do it or reset the root password without shutting down the system.
I'm running AIX 5.3 password length 8 characters , please suggest anything else except to brute force or dictionary attack password methods I have access to HMC and sever's console also there is a VIO sever run on same server but different lpar I have access to ASMI you can say anything else except the root's password:wall:

I don't suppose anyone has the ability to sudo su or visudo on this system?

I don't think that sudo is installed on the sever , But What I meant we always do su to the userID which the application is running under it's ID then we stop the application, As I said earlier we have lost the root's password and the user's password which the application is running under it.

There's no way to alter root's settings without root, that being kind of the point.

Ouch!! tough lesson
@Corona688 are you sure there is no other way to achieve this without shutting down the system as I said earlier I have full access to HMC , ASMI , VIO LPAR on same sever , SAN storage (Rootvg is DAS HDD ), a non privileged user and any thing else except the root's password and user's id which the application is running under it.
All I want to at least shutdown the application gracefully due to sensitivity of data if no other way to get root's password.
I do know that brute force connections might crack the password but it's virtually may lead to unspecified time .
Otherwise
We have reached a dead end.
Gone baby gone.:wall:

system needs downtime :frowning:
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