Is it possible to close/disable/archive a level 1 site?
Deleting a level 1 site must be performed by an Admin of the organisation.
The option is available from Data Collection Portal > Dashboards > select a site > Danger zone

A deleted site will be withdrawn from your list of level 1 sites. You will not have access to data from the deleted site anymore (except via the Data Sharing feature). We recommend that you extract any history that you might need.
As a reminder, a site should only be deleted if the tags have been removed. Please follow this procedure before contacting the support.
Please note that scheduled exports configured to export data from a level 1 site that is being deleted will be automatically suspended (even if they include other sites that are still live).
You must therefore review your export configurations before deleting sites and make sure those sites are no longer in use.