There may be an easier method if you currently have or are willing to install the Freeware program
CCleaner.
In CCleaner, select the third tab on the left "Tools", then select "Startup" from the second column, and choose "Context Menu" from the tabs across the top. If the item you wish to remove is in the list select it and, I suggest you just, choose disable.
Note that there can be several that have the same applications assigned but they apply at different times, such as if you are right-clicking on a folder versus right-clicking on an actual file. After you are sure you have disabled the right ones and made sure everything is working for a few days, then you can always come back and actually Delete.