Install
Meziantou.Framework.Win32.CredentialManager
and follow these steps.
CredentialManager.WriteCredential(
applicationName: "CredentialManagerTests",
userName: "meziantou",
secret: "Pa$$w0rd",
comment: "Test",
persistence: CredentialPersistence.LocalMachine);
var cred = CredentialManager.ReadCredential(applicationName: "CredentialManagerTests");
Console.WriteLine(cred.UserName);
Console.WriteLine(cred.Password);
CredentialManager.DeleteCredential(applicationName: "CredentialManagerTests");