remove method
Removes an entry from persistent storage.
Returns false if the platform implementation can definitively determine
that removing the preference failed. A return value of true indicates
either that the value was removed successfully, or that the underlying
platform API does not report success or failure.
Implementation
Future<bool> remove(String key) {
final prefixedKey = '$_prefix$key';
_preferenceCache.remove(key);
return _store.remove(prefixedKey);
}