There is no way to change the Admin password without being logged in as Admin on the HMI.
To get around this, load the project onto your PC with Xpress Manager from a Compact Flash card reader.
It'll appear under Remote machines. Highlight it and click left arrow to copy it to your PC as a local project.
Double click it to load the project.
The Xpress Shell should display.
In the Xpress Shell go to User Admin > User
Here you can change the passwords. Scroll down and press OK.
Security options sets the user level on power-up. Users can change this to Admin here.
This has the added benefit that when the application starts with Admin as the startup user, it always stops at the shell with Admin rights and they can change the ip address.
Transfer the project to the Remote to the Compact Flash card and then restart the HMI with the CF card loaded.
After the HMI boots to the shell, users can then go into the network settings and change the IP address there and can change the startup user from admin back to the original user level. The next time the HMI boots, it can then boot directly to the application with Xpress Runtime instead of the shell.