You can use the "<strong>Delete</strong>" action (usually bound to Delete key) to clear z-offsets of selected vertices.<br/>
You can toggle the Visual vertices display from the <ahref="../general/rendering_toolbar.html">Rendering toolbar</a> or the "<ahref="../../actions.html#visualverts"><strong>Toggle Visual Vertices</strong></a>" action.<br/>
Visual vertices with height offset (e.g. with some values in "zceiling" or "zfloor" UDMF fields) are colored using the "Info Line" color. Visual vertices without offsets are colored using the "Vertex" color. You can change these colors in Preferences -> Appearance.</p>