To remove these context menu entries .,go to run>and type regedit and open the registry editor.
Goto Hkey_classes_root and then expand the * node by clicking on the + sign near it .
Then expand the shellex node and then expand the contextmenuhandlers node.
There you will be able to see various applications which have created context menu .Just remove the key which you do not want to appear as the context menu by exporting it out of the registry. Now refresh My Computer and now you will not be able to see these context menu.This will hold for files .
For folders go to Hkey_classes_root and then expand the folder node and then repeat the same.