1 The user does not get a notification
When you Unmatch someone on Tinder the process happens silently and the user does not get notified.
2 You disappear from the match list
When you Unmatch a person on Tinder you disappear from that person's match list. When that person checks their matches they won't find your account there.
3 You won't be able to send them a message
When you unmatch someone on Tinder the user will disappear from your own match list, and so it won't be possible to send them a message.
4 You won't find them again during search
According to Wikihow, when you unmatch a person they won't show up again on your swipe screen unless you delete your account and start over.
5 The person might not notice
If the person has many matches in their list then they might not notice that someone has disappeared from their list unless they scan the list looking for you.
6 You won't be able to read previous messages
Both you and the person you unmatched won't be able to read the message thread that you exchanged as it will disappear.
7 Permanent block
The unmatch option is considered a permanent block. It's similar to Facebook's block option.