The departure of a Level 1 User can remove the organisation's only practical route into its sponsor licence. The legal difficulty is not confined to the login: sponsored worker changes, licence notifications and urgent personnel updates may continue to fall due while the account is inaccessible.
Home Office guidance deals expressly with the situation in which the only Level 1 User has left. It does not authorise another employee to inherit that person's credentials. It identifies a separate change of circumstances procedure and makes clear that the sponsor must maintain at least 1 Level 1 User at all times.