I have a below enum in TypeScript:

enum RoleTypes {
  None,
  Admin,
  SuperAdmin
}

When I run the following code:

var roleName = RoleTypes[RoleTypes.SuperAdmin];

the value of the variable roleName is SuperAdmin.

Is it possible to change it to a custom name 'Super Administrator', and how do I do this?

Combining Markus's answer with Use Enum as restricted key type in Typescript, you can use eithers of the following syntaxes to constrain object keys

Either { [key in RoleTypes]: string } or Record<RoleTypes, string>

enum RoleTypes {
  None,
  Admin,
  SuperAdmin
}

let RoleTypesDisplay: Record<RoleTypes, string> = {
    [RoleTypes.None]: "None",
    [RoleTypes.Admin]: "Administrator",
    [RoleTypes.SuperAdmin]: "Super Admin",
};

var roleName = RoleTypesDisplay[RoleTypes.SuperAdmin];

console.log(roleName);

Demo in TS Playground