How to set enum to null

Make your variable nullable. Like:

Color? color = null;

or

Nullable<Color> color = null;

You can either use the "?" operator for a nullable type.

public Color? myColor = null;

Or use the standard practice for enums that cannot be null by having the FIRST value in the enum (aka 0) be the default value. For example in a case of color None.

public Color myColor = Color.None;

If this is C#, it won't work: enums are value types, and can't be null.

The normal options are to add a None member:

public enum Color
{
  None,
  Red,
  Green,
  Yellow
}

Color color = Color.None;

...or to use Nullable:

Color? color = null;