I have heard of several occurrences of a fairly new person accidentally deleting data from Graph Studio. The common pattern seems to be that you are traversing through data using the Explore Graph pane, and you want to clear some selections, and you click the Delete button instead of the Hide button. Even though there is a confirmation required, this mistake has been made several times by people that incorrectly think they are just deleting it from their view.
I humbly suggest that there should be an option to disable this, since for an established schema, you would seldom want to delete data using the Explore Graph pane.