Community can be deleted at any point. After deletion we have the community in list for seven days and it gets deleted permanently after 7 days. In the grace period of seven days you can retrieve the community back to active list.
To delete a Community, go To:
Login >> Communities
Open the communities folder, you will find all the communities listed.
Click on Delete.
Click on Yes and community will be deleted.
You can retrieve the community back after clicking on Restore option.