A 'my site' has somehow been set up incorrectly on SP2013 OnPrem. I would like to delete the site for this particular user, to allow him to create the site again, presumably correctly this time.
Can somebody tell me the steps for doing so?
Like all site collections they will show up in the list all site collections area with central admin. You can delete the site from there. Its been awhile since I have done this, but if I remember correctly when the user next tries to visit the site it will see that it doesn't exist and try to recreate it. If that is not the case, and the user gets a 404, you then just need to clear our the personal site property within the user profiles.