How would I model my class diagraman where Inside said class I create two more classes? Here is my code in kotlin:
class Enum {
enum class Electrodoméstico{
Lavadora,
Microondas,
Refrigerador
}
enum class Colores{
Blanco,
Negro,
Gris
}
}
I also have to mention that my class Enum is in association with my super class Electrodoméstico where I implement my enum classes Color and Electrodoméstico.

The UML 2.5 spec states this on p. 100:
I'm using EA for modeling which allows to enlarge the class frame to fit the nested enums inside. However, it does not allow to create a named compartment. But honestly the rendering will be obvious for any reader also without the label.
You could as well just abstract the whole thing. There is probably no force to have the enums encapsulated. So you could well model it as you did with associations. Your code would then just be some implementation variant.