Here's how it works. We want to know if it is a good decision to sack Thomas Tuchel. So, we're placing bets for two situations: whether England will get to the final WITH him or WITHOUT him.
If Tuchel is the England manager at the start of the Euros, then the "Assuming Tuchel sacked" market will be CANCELLED AND ALL BETTORS WILL BE REFUNDED. This is because - of course - we will never know what would have happened in the other situation!
If Tuchel is sacked as England manager, then likewise, the "Assuming Tuchel NOT sacked" market will be cancelled and all bettors will be refunded. So, at most one of these markets will be resolved based on the decision to sack Tuchel - that's what "decision market" means. If you're a person contemplating whether he should be sacked, then, you can look at this market and see the consensus opinion on his effect on the team.
1,000@HamishTodd I don't think this market type allows you to cancel specific options (you would have to cancel all or none). You should remake this using the "set" market type.