From HowToGeek

If your IT department has set a password that prevents you from removing or just unloading Trend Micro Office Scan from your computer, you can often make a small change to the INI file that will reset the password to "1"

Instructions

Navigate to the installed directory, like C:\Program Files\Trend Micro\OfficeScan Client. Once there, look for a file named ofcscan.ini and open it up in notepad.

Note: Sometimes the ofcscan.ini file can be found in the Windows directory instead.

Search through the file using Ctrl+F to find "Unload_Pwd", and then you should see a section that looks like this:

Change these two lines to a value of "70" (without the quotes):

Uninstall_Pwd=70 Unload_Pwd=70

When you are done the file should look like this:

Now you should be able to unload Office Scan by right-clicking on the icon and choosing Unload, or you can uninstall the software from the control panel.

When you are prompted for the password, enter "1" (without the quotes)

Note that you probably shouldn't do this as it might violate the policies and procedures set by the pointy-haired bosses at work. If you do remove Trend Micro, make sure you have some type of alternate anti-virus solution installed.