If the application refuses to uninstall properly, then the approach needs to be different than regular Add/Remove Programs.
For these cases there are products that bypass these restrictions and remove the software in different ways.
I would like to recommend Your Uninstaller!. Beside the fact that it will remove applications, it will also clean your hard drive for junk files and perform regular maintenance over your computer. The built-in tool, called Advanced Uninstall, is the part needed to remove TI-73 Tutor. If the entry of the product in question is broken, then Your Uninstaller will detect this problem and mark its icon with a yellow exclamation mark.
Please right click the icon and choose Advanced Uninstall or click the respective button found on the main interface and let it do its magic.