If the Windows uninstaller does not work or fails, things can get difficult. The Trend Micro Diagnostic Toolkit for the product at hand may be necessary. For the Titanium product, it is available here for 32-bit and 64-bit:
http://esupport.trendmicro.com/solution/en-us/1059841.aspx
And a general 32-bit download, at least for some versions, appears here:
http://solutionfile.trendmicro.com/solutionfile/EN-1037161/32bit.exe
And another, a general agent remover, very general: