Currently, when modifying a recurring event you can either delete all occurrences or the current occurrence. It would be nice to be able to delete the future events, but leave those that have already occurred unchanged.
I landed here because I was looking for this feature as well. Another way to accomplish the same thing (which may not work for all events) is to edit the recurrence end date, as mentioned here: http://forums.mozillazine.org/viewtopic.php?f=46&t=2355617
I ABSOLUTELY support this. I have several recurring business meetings that get scheduled by others for ridiculously long lengths of time, then a year later, they end, and I have to delete them one-by-one until the end of the imported schedule. It is a massive headache, especially for events where people put no end dates on them. I've had this option on other calendars, and it can be a massive time saver. PLEASE impliment it.
Also, to dkbg's point, that only works for events that you create. I have several repeating meetings that are either no longer going or that I am no longer working with that were sent to me by someone else. You can't edit events that you accept from someone else. All you can do is delete them.
This is an absolutely vital feature to be able to use recurring events. Currently, not only is there no way to edit future events, but you can't access the "edit only this event" and "edit all" options when dragging to change an event's date/time, it just defaults to edit only this. I would suggest the same popup allowing you to select "only this event" and "all" options when editing events in this way, along with the proposed "future events" option.
There also needs to be a way to detach a recurring event entirely to move it to a different calendar (there may be other uses, but that is the main one I can think of). I'm going to open a separate feature request for this. This wouldn't be as necessary if copy and paste didn't work for recurring events - I am also submitting a bug report for that.
Totally agree, I want Thunderbird to be my single calendar program, but the absence of "Delete This and all following events" forces me to go back to Outlook online to do so.
For business use, we frequently use recurring events, so we also need to end them easily.