Problem Statement:

GL account was created as primary cost instead of non-operating with cost element category 01 (Primary Cost/Cost Reducing Expenses) and lot of postings happened before business could realize the mistake.

System was not allow to change the master data back to the non-operating since data available in costing tables (CSKA, CSKB and COEP) and there was significant impact on month end closing in the production system.

Applied SAP notes which could fix the FI tables but did not fix the CO tables, we followed below approach after consulting with SAP: 

1. Delimit the Cost element by a program.
2. Delete CO views on the documents by using the standard program
3. GL account switched to Non-Operating Expense or Income type and  no records were found in CO tables (CKSA,CKSB and COEP).