I am not able to remove xcode 4.3.2. where i tried the below comands on termnal but it did't work
sudo <Xcode>/Library/uninstall-devtools --mode=all
sudo /path/to/Xcode/Library/uninstall-devtools --mode=all
sudo /Developer/Library/uninstall-devtools --mode=all
sudo /Xcode4/Library/uninstall-devtools --mode=all
Dashcode and Quartz Composer are not part of Xcode 4.3.2's application bundle. Deleting Xcode is not going to delete them. You are going to have to remove Dashcode and Quartz Composer separately.
Instruments is part of Xcode 4.3.2's app bundle so deleting Xcode should also delete Instruments. I do not have Instruments on my dock so I don't know if trashing Xcode removes the Instruments dock icon. Does clicking the Instruments dock icon launch Instruments? Do you have other versions of Xcode installed?