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.
Deleted community will be moved to the recycle bin. Recycle bin will be seen only if there are any deleted community/communities.You can retrieve the community back after clicking on Restore option.
If you want to delete the community completely, you can click on Empty Recycle Bin option. Communities once permanently deleted cannot be restored back.