Right now, community owners can only unpublish communities, and not completely delete them. When a community is unpublished, it will be hidden from the public, including you and your members. You have the option of re-publishing it later on.

For steps on how to unpublish, check out this article: Unpublishing your Community

If you want your community to be permanently deleted, you may send a request to the team through support@beam.gg.