When you delete an item from your Office 365 account, it’s not immediately permanently deleted. Instead, it’s first moved to a special folder called the recycle bin (or trash). Items stay in the recycle bin for 30 days, giving you a chance to restore them if you accidentally delete them. After 30 days, items are permanently deleted and can’t be recovered.
This 30-day period is called soft delete. To permanently delete an item immediately, you can hard delete it.