Should I delete lost GPG key from GitHub?

I’ve been using GPG key for a while to sign commits on GitHub. However, I recently lost it by accident when moving data around. It haven’t leaked anywhere and signed commits can be trusted, I just don’t have private key anymore.

So, should I delete public key from my GitHub account? This will remove “signed” mark from commits which seems to be wrong in my case when I just can’t make any new commits with it.