OK, so here's how to split stackable Items.
You hold down shift+ctrl and then click on the Item.
NOW, you move your mouse left or right and that peels off more and more the farther away you move your mouse, so you can pull 400 bullets out of a Stack of 2000.
Sometimes it hasn't wanted to work on somethings that claim stackability. However, it has always worked on Ammo.
And for the original Question of how to remove a Chat channel. well you can only remove the Temporary ones made by people. It least I think that is all you can remove.
If you foolishly joined Group SupaN00b and how you just don't want to have to put up with having that group in the way any more, cause you have heard WAY too much about what Rollarats Squeaks remind people of, you'll notice a little Button on lower left of the Friends that lit up RED when you joined that Group, Called TEMP GROUP. Just click on TEMP GROUP and any player made channels are gone!
Hope that helped, and would like to see other sneaky codes,..and less Uber talk, there are more than enough threads for that, quit wasting our time on this thread, unless you are going to add a Code too