Is there a possibility to revoke one's vote-to-reopen a question?
What is the procedure and the correct indications to follow?
No, you cannot revoke a vote to re-open. It's similar to casting a "Looks Good" vote on a post in the Low Quality Post review queue (say). Once it's cast, you can't take it back. However, you can retract close votes (since Jun 2013).
Don't fret though, because you can cast a vote to close if the question gets re-opened, perhaps adding a comment to the post suggesting some support for your voting behaviour.