I am the portal owner/administrator - why can't I close other people's tasks?

I am the portal owner/administrator - why can't I close other people's tasks?

I have a bunch of tasks sitting there from someone else who isn't around atm, they are completed but I can't close them.
I can only add notes.
 
I used to use iTeamwork, which is not nearly as complex as Zoho, but it did give the managers complete control over all user's tasks.  Am I doing something wrong?