I'm not finding much support for custom autoresponder options in the API docs.
Specifically, I want to be able to remove someone from a series of autoresponder emails prematurely based on a certain web event. For example, if they start the autoresponder, then signup for whatever we are pushing, then there is no need to continue sending the series, so I want to remove them from getting the rest.
Is there a way to do that with the APIs and if so, can you point me in the right direction?
The only Autoresponder management currently available through the API is for the initial Welcome message, described here. Managing profile change autoresponder messages is only currently avalaible through the product UI, I'm not sure that the functionality you are seeking is available even through the UI.
Here a link to series of FAQs regarding autoresponder in the product knowledgebase.