How to create single-record Contentful content models
Unlike DatoCMS and Contentstack, you cannot restrict a Contentful content model to be used to create a single record, only multiple (as per design). As a workaround you can add a text field (with a dropdown appearance for example) to the model which only accepts a single exact value, marked as required and unique. It won't prevent creating additional records, but it will prevent publishing more than one.