I'm not up to speed on Claude's features. Can I, from the prompt, quickly remove those permissions and then re-add them (i.e. one command to drop, and one command to re-add)?

Yeah, you can type `/permisssions` and do it there. Or you can make a custom slash command, or just ask Claude to do it. You can also set it when you launch a claude session, there are a dozen ways to do anything.