If the EMS admin password has been lost, it is easy to recover. In EMS all local users and their passwords stored in the users.conf file by default. You can find correct file in the tibemsd.conf:
users = "C:/tibco/tibco/cfgmgmt/ems/data/users.conf"

In the users.conf find admin user:
and remove encrypted password between colons:

Then restart EMS daemon. Connect to your EMS using EMS Administration Tool and login as admin without password:
> connect
Login name (admin):
Connected to: tcp://localhost:7222

Then set a new password for admin:
tcp://localhost:7222> set password admin 123
Password of user 'admin' has been modified

If you manage EMS in the TIBCO Administrator, then you need to change EMS admin password there. Start TIBCO DomainUtility, select “TIBCO EMS Plugin”, “Update TIBCO EMS Server”, press “Next”. Select domain and enter domain (not EMS!) admin user name and password. Select EMS server to update, and change EMS password there, test connection on the next screen and press “Next” to save new configuration.

So, EMS password recovery is very simple, isn’t it?