If someone asks you for a favor and you have no plans to fulfill that request, tell that person NO. Be honest about your intentions. Do not ignore the plea. Do not keep him/her hanging. That’s just RUDE.
Speaking directly may seem harsh, but it is the more emotionally healthy option. For everyone involved.
Again, if you do not want to do something that someone asked you to do, just say no. At least then the person requesting the favor knows where you stand and can move on.