Hi
On the time tracking report, there is no option to hide the sub-task details.
We have issues which are broken down into tens of sub-tasks and Project managers are not necessarily interested in time tracking of sub-tasks moreover time tracking report also becomes huge with unwanted information.
So, it is possible any way to hide sub-task information. The parent issue anyway shows the accumulated time remaining and time spent metrices which are of primary importance to PMs.
Rahul