Global Calculated Metrics - Warn before allowing to delete

If an admin is in the Report Suites > Edit Settings > General > Calculated Metrics > Under Manage, if X (delete) is selected, a warning should appear that says something like - any reports and/or dashboards that are using this metric will be affected, are you sure you want to delete? -- 

Currently, if an admin selects the X there is no way of recalling the deletion.  We had a number of dashboards that were affected by this removal.