GP 2013 SP2 adds the ability to hide the SmartList pane along with the ability to resize the pane. If you aren’t yet on GP 2013 SP2, the Support Debugging Tool will let you resize the pane on earlier versions.
Weekly Dynamic: SmartList Splitter
Tips & Hidden FeaturesReporting & BIGP 2013
Archived post from 2013. Dynamics GP and the links it points to have changed since; check current documentation before relying on version-specific steps.