basically the name says it all. im trying to check out a different branch on plastic scm

but I get an error because there are pending changes.
If i go undo the changes:

even after pressing undo, the change persists, and it won’t go away.
If I try to shelf the change:

it gives me an error message:

So far, I can’t figure out how to get my project back to a clean state so I can change branches.
Is there a command to reset all changes and get the project to a clean point? what do you do when you have plastic giving error messages but resolving them doesn’t work?