Off the top of my head, I have to assume that there is no disabling on the Alias tab (if there is and you're asking me about it, you deserve a slap).
While it's possible... I'm not sure I will implement it... Aliases are called VERY often (every spell that has an alias, it is checked). To add the disable, I have to add another check to every single alias call. If you can give me a big enough reason that people would use it, I can add it, otherwise I highly doubt it. It'll just burn up extra CPU calls that aren't needed.
Realistically, if your group changes, you could edit the 1 alias and be done with it.