A family of Microsoft presentation graphics products that offer tools for creating presentations and adding graphic effects like multimedia objects and special effects with text.
I wonder if each of the color schemes in "this presentation" is tied to a different slide master. If so, deleting that master might remove the associated color scheme. I'm not sure, off the top of my head. I'd have to do some mucking about to test it.
Anyway, yes, you have to edit the XML to remove these extra schemes. I'll try to find a few minutes today to set up a file with extra colors and then poke around in the XML. Actually, if you can just email me your file, that might be easier. echos at indy dot net is the address to use, and if you'd include the text of your original post so I can remember what I'm doing, that would help!
I suspect the process will be similar to that described here: http://www.echosvoice.com/2007/addcolorstotheme.htm (click the link for Click here to get a PDF with instructions for adding color schemes to a theme). This describes adding a color scheme to the XML, so I think you'd probably look in the same place to delete the extra color sheme as well.
That said, I'm with Christine in that you can't really lock the theme so that it cannot be edited. I mean, to change the color scheme, you'd simply select another. Or choose Create New Theme Colors and make a new one that's based on the current one. If you're just using "locked" to mean you cannot right-click and edit the color scheme in the Colors dropdown, though, then okay, you just need the color scheme to be part of the theme.
-- Echo [MS PPT MVP] http://www.echosvoice.com