crt.sh is a log monitor, a reporter on historical facts about which certificates were logged. Let’s Encrypt automatically logs every certificate it issues, so your certificate (with the example.com domain name) will appear in crt.sh forever.
Revoking the certificate doesn’t change the fact that it was issued. All that happens when you ask for revocation is that Let’s Encrypt changes the Certificate Status reported by its OCSP responder to say revoked for that certificate. Systems which check OCSP will notice some time within the refresh period of OCSP, several days.
You should ask Let’s Encrypt to revoke if you believe your private key may have been compromised, or if the certificate should never have been issued (e.g. an administrator got the cert without permission at your company trying to be helpful, that’s happened at Facebook) but otherwise in most scenarios there’s no need to revoke, just let the old certificates expire naturally.
I’m intrigued as to why users feel they “ought” to revoke, and also, why they expect revoking to make things vanish off crt.sh as I have seen this idea more than once now.