After system refresh/copy i found that ST03 still showing the name of source in Workload Analysis menu. Here is some work around to delete the source.
Go to ST03n–
Change to Expert mode –
Go to Collector and Performance DB — Performance Database — Workload Collector Data —Contents
Select all the right hand side value of source system & delete all.
Now your source system is removed from ST03 Workload menu.
After deleting the source system you got a popup with error “No System Load Data Available”.
Adding Present System in Workload Menu.
Schedule the SAP standard job “SAP_COLLECTOR_FOR_PERFMONITOR” from SM36 in hourly basis.
This job runs the ABAP report “RSCOLL00” , Collect the data and update your Workload Menu.