Nativescript application-setting module: setString('attribute_name', default value) do not return default value after remove('attribute_name') - nativescript

Question

I noticed this anomaly working with application-settings module on a
nativescript (8.1.2) /angular project.
Having this code:
import { getString} from '#nativescript/core/application-settings';
remove("attribute_name_string")
let attribute_name_string = getString("attribute_name_string","DEFAULT VALUE")
console.log("Print My Local Atribute = " + attribute_name_string)
I was expected the result to be:
Print My Local Atribute = DEFAULT VALUE
but it was
Print My Local Atribute =
The same for setNumber
import { setNumber} from '#nativescript/core/application-settings';
remove("attribute_name_number")
let attribute_name_number = getNumber("attribute_name_number", 121)
console.log("Print My Local Atribute Number = " + attribute_name_number)
I was expected the result to be:
Print My Local Atribute Number = 121
but it was
Print My Local Atribute Number = 0
Two questions here:
Why this strange behaviour (anomaly)?
How can I clear my variables and get the default value afterwards ?
Please take in consideration the official documentation:
A default value can be provided in case there is no existing value.
/**
* Gets a value (if existing) for a key as a String Object.
A default value can be provided in case there is no existing value.
* #param key The key to check for.
* #param defaultValue An optional value to be returned in case there is no existing value.
*/
export function getString(key: string, defaultValue?: string): string;
and
/**
* Removes a value (if existing) for a key.
* #param key The key to check for.
*/
export function remove(key: string): void;