The first thing that you want to do is to open the Start menu, start typing the word "programs" (without quotes), until Add or remove programs appears in the Best match category, then look for System Transparency in that list. The application might also be under a different name such as Transparency Project or basically anything with transparency in the title.
In case that doesn't work, press Ctrl + Shift + Esc to open the Task Manager, click the button in the lower-left corner that says "More details", then look for "systemtransparency" in one word, either in the Processes tab or in the Details Tab. Once you found it, right-click the entry, then choose the "Open file location" option and see if you can find an uninstaller there or the program's real name.
Lastly, if you want to disable the Windows transparency options altogether, click the Start button, type "color" (without quotes) until Color Settings appears in the Best Match section, then click that entry. In the window that opens up, scroll down to the More Options category and toggle the Transparency effects switch to off.
