I have created a Sanity.io CMS, I have made some alterations to the schema after content had already been entered. The problem now is that the content is still saved somewhere inside the cms and I have no way to remove it.
There are several ways of deleting documents which are no longer visible in the Studio:
sanity documents query '*[_type == "unwantedType"]._id'
and then sanity documents delete [list-of-unwanted-doc-ids]