What version of LabView are you using?
Are you rellay using a subpanel (introduced in 7.0) or are you using a subVI?
If you're using a subpanel in LabView 7.0, on the front panel of the calling VI, add a subpanel from the Containers palette, right-click on the subpanel, goto Visible Items, and turn them all off, one-by-one.
If you're using a subVI, from the front panel of that subVI, goto File >> VI Properties >> Category >> Window Appearance >> Customize and turn off Window Has Title Bar, Show Menu Bar, Show Scroll Bars, Show Toolbar When Running, Allow User to Close, Resize, and Minimize Window.