How do you delete or remove statuses from a past incarnation of an instance/account?

Hi all.

Installed and setup a Pleroma instance and posted to test it all worked. I then followed the admin account from a Mastodon instance, and could see the status I had posted, so could confirm that the instance was working. I then went about reinstalling the instance, this time looking to document the whole process. Even though the account I have on Mastodon unfollowed the Pleroma account, when I search for the Pleroma account I can still see the test statuses I had posted before reinstalling.

What is the process in removing these test posts? I had a similar issue with a WriteFreely instance, and had to contact the admins of the instance which had first discovered it to 'refresh' their own instance, which then removed all previous posts. Is it the same with Pleroma? If so, how would I find out which instance needs refreshed to remove the old posts?