Are you talking about the Time Remaining display on the side bar? The text for that field is in the Modify Text Labels... tool in the Theme Editor of Presenter. You can change it to whatever you want, but you may want to keep a record of what the default text labels are, as there is no restore to default option. The Elapsed Time field is what you would want to change. I have seen this modified to show no text, copyright information or other general info.
It looks you are asking about the duration that is shown in Thumb and outline tab.
Currently there is no way to get rid of it.
However you may completely remove the Outline\Thumb tabs . Goto Themes->Panes, uncheck the ouline and Thumb checkbox.
Adobe Engineering Team