In Acumatica all passwords are stored as a Hash, so even if you get database, you are not able to login with user password.
But in case of trouble you can reset it to new one directly in the database. Just execute this query against the sql:
UPDATE Users SET Password = '123', LockedOutDate =null WHERE Username = 'admin'
Don’t worry about clear text password – Acumatica will automatically calculate new hash on first login operation.
LockedOutDate is field where system stores last unsuccessful login attempt date-time. So if your user is locked out you can use this statement to unlock it.