Which of the following is NOT a lawful way for an unsentenced inmate to be released?

The option indicating "Time served" is the correct response as it does not represent a lawful method for releasing an unsentenced inmate. When an inmate is deemed unsentenced, it means they have not yet been convicted, and therefore, their release cannot be solely based on the amount of time they have already spent in custody.

In contrast, secured bonds, written promises, and unsecured bonds are recognized legal methods for release in circumstances involving unsentenced individuals. A secured bond requires a monetary guarantee to be posted; a written promise allows individuals to agree to return for court proceedings without the need for bail, and an unsecured bond allows for release under the promise of future court appearance without upfront payment, showcasing the legal mechanisms available for managing unsentenced individuals. Time served, however, is more appropriate for sentenced individuals who have completed their punishment, making it inapplicable in this scenario.