What else can I do while a show is playing?

You can remove sequences from a show without making the show restart by moving the sequence files to be removed into a different directory.  When the show tries to play that sequence, it won't be able to load it, so it will just go on to the next sequence.  You can also just delete the sequence file if you have a backup or don't want it anymore.  Again, this won't work for a background sequence, which is only loaded once when the show starts.