Might very well depend on which version of Object Dock you're running. On ODPlus v1.9, go into Configure Object Dock, "General" on the left list, "Miscellaneous Options" button about a third of the way down. In popup window that appears, underneath "Label Fonts", uncheck "Show labels on zooming docks".
Sorry, I'm not familiar with versions other than Plus1.9, so if you're running one of the others and don't see that option someone else will have to help.