I just accidentally made a new master parameter dial for something and I'd like to delete it - anyone know how to do this?

Edited to add, i did this in poser pro, and on a prop

Well, if it's a Full Body Morph you can't do it in the Parameters Panel, because Delete Morph is grayed out for some reason when it's in the Body actor instead of a body part (at least in Poser 8). But you can do it in the Hierarchy Panel. Make sure Show Parameters is checked so you can see the dials in Hierarchy, then select the parameter in question and hit the Delete or Backspace key. Just like deleting anything else in Hierarchy.

In Poser, open the Hierarchy Editor, select the box that says "Show All Parameters" (not "Show Parameters"), select the channel (dial) you want to delete, then press the Delete key.

Alternatively, if you save a cr2 or pz3, you can use a cr2 editor (eg CR2Buider, Cr2Editor, etc)  to delete the channel from the file.