The tickets returned from Expo are in the same order as the notifications you sent, as stated in the docs:
The requests above will respond with a JSON object with two optional fields,
dataanderrors.datawill contain an array of push tickets in the same order in which the messages were sent (or one push ticket object, if you send a single message to a single recipient).
So you would remove the token at the same position in the array of notifications you sent