Hello,
The install manager may remain on your computer until the actual Catalyst center is removed. However, I do not recommend this as it is the program that manages the graphics card installed on your computer.
Some programs do use their own version of an installer, this may be why it looks different than what you are used to. Pay attention to which folder the program installs in (normally C:\Programs). Be sure to set a Restore Point before installing/uninstalling as well. You will find steps here: http://windows.microsoft.com/en-us/windows7/create-a-restore-point
If you can't be sure then be safe. Hope this helps.