Yes, you're missing the fact that 3.0 is an add-on to 2.0 and that you
cannot remove 2.0. (Same thing goes for 3.5, BTW)
As for 1.1, whether or not you can remove that safely depends on what (if
any) software you have installed that requires 1.1.
How did 1.1 get installed on your machine in the first place? If it was
installed with, for example, Visual Studio .NET 2003, that product will not
function without .NET Framework 1.1.

3. 0 is 2.0, or rather sits on top of 2.0. 3.5 is the same way. If you
delete 2.0, your 3.x apps will quite working.

You can get rid of 1.1, as long as you do not have an application that uses
it.

*************************************************