To pause the presentation simply click on the Pause Share Screen button on the GP5 interface.
If there is no Pause Share Screen button but there is a Share Screen button on the GP5 interface then you have not yet stared sharing in the meeting.
To resume the paused presentation simply click the Share Screen button on the GP5 interface.
Note: The guests will stay connected to the meeting but will see nothing while the host has paused presentation. The guest viewer window will re-appear once the presentation is resumed.