Try "admin" as password.
-or-
from this
link
Following are the steps to set a password in trend micro internet security:
- Click Start => Programs or All Programs => Trend Micro Internet Security => Trend Micro Internet Security.
- Double-click the Trend Micro Internet Security icon n the lower right corner of your screen.
- Click Other Settings on the left panel of the window and click Password on the right.
- Click Settings under that.
- Put a checkmark in the Activate password protection checkbox.
- Type your desired password and re-type it to confirm.
- Click OK
- Close the Trend Micro Internet Security main console.
This might work, or the link has a few other alternatives if the existing password has locked this option out/.