Hey Gertjan, thanks for getting in touch!
Great question — yes, it is definitely possible to create an event that repeats every six weeks and ends on a specific date. There’s a great overview of all the recurrence options in this post, if you’re interested.
And, yes, you are able to delete events from a recurring series. In other words, if you need to delete one single instance of the series, then you are able to exactly that.
Does this help answer your questions? Please let me know. 🙂
Cheers!
Geoff