I think we should have the ability to cancel or "un-schedule" friendly matches, so long as it is done well in advance. I think 96 hours (4 days) prior to match start time is adequate, after which no changes could be made. Of course, a message should pop up in both team's club newsfeed about any cancellation.
Every friendly tournament I have organized, at least once someone arranges their friendly with the wrong team, presumably by accident, usually in the first round. There are probably other reasons for canceling a friendly match, but this is the most important I think...
