I accidentally deleted a custom metric, report, or dashboard from Explore. Can I recover it?
No. Deletions in Explore are irreversible and cannot be recovered. If you remember the formula used, recreate the metrics, reports, or dashboards. They will still pull the same data as before.
While metrics and attributes can be deleted from Explore, data can not be deleted. For more information, see the article: How do I delete data from Explore?