If you own the domain, then it will he yours to do what you like with. If its a free subdomain I assume it gets deleted from the system and anyone could use it again.
On a custom domain, it’s just unassigned. We don’t own or control your own domain names, so the domain name itself doesn’t disappear.
For subdomains, there isn’t really a difference. Unassigned and deleted are the same thing.
When you delete a domain from your account by hand, it’s removed instantly. When you deactivate an account, the account is more or less frozen in-place. So any domain names assigned to the account will stay assigned until either the domain is deleted by hand or the whole account is gone.
It is assigned to your domain, but is only accessible when the domain and SSL certificate are on the same hosting account. So if you change hosts/hosting accounts, you will either need to get a new certificate or copy and paste the private key and certificate to the new account.
What @Greenreader9 said. The SSL certificate is removed from the hosting servers when the domain is unassigned from the hosting account.
The SSL certificate itself remains though. If you got it through our Free SSL Certificates tools, you can retrieve the certificate from there and upload it to a different account.