You can delete your organization within the "Organization Settings". Simply click on your profile picture in the lower left corner and select the option "Organization Settings" to open it.
After clicking the more button (symbol: three dots) next to "Organization Settings" and selecting the option "Delete this Organization", a password query will pop up, asking for consent to delete all data.
Deleting an organization
Warning: If you confirm this query, all data of your organization will be irrevocably deleted and cannot be restored. In case you are included in more than one organization, make sure you are in the organization you want to delete. You can find out how to switch between different organizations here.
Dialog box to confirm the deletion process