Tasks assigned to you by other users cannot be removed by you. Instead, when you use Remove Completed, these tasks will return to their original owner.
To delete task or project open it for editing by clicking task text or project title. Then you will see the "Delete" button at the bottom of the expanded task.
Nobody will see your projects or tasks until you assign task to that person (drag task and drop it on teammate). In Business Account you may select if item is private or shared. Private items stay private and nobody can see them. Shared items are visible to whole Business team.
With Free and Premium accounts your tasks are not shared. You need to explicitly assign task to other person. To share tasks and projects with team upgrade to HiTask Business.
Just click on Settings link on top of the screen while you're logged into HiTask. On Settings screen you can adjust your preferences such as date and time format, starting day of the week.
While you are modifying an item, look for "Recurring" selection below the dates. Note that "recurring" option will not appear until you set the start date.