Can we delete KPIs from the system?
KPIs shouldn't really be deleted from the system since they sit separately from the rollover and therefore, deleting a KPI will delete it for good in all periods . i.e you will not be able to go back and review the KPI in any archive periods.
There is the ability to 'archive' KPIs by making the KPI Inactive. What this does is that it will hide it from the KPI list and all screens like your KPI update screen and reports.
You can filter them out by using the 'Show Archived KPIs only' filter: