You cannot delete costing codes from Access Expense for auditing purposes, but you can hide them so users cannot select or see them.
Click Settings, then click Costing Import.
Click Costing Template on the right-hand side to download it.
Select Include all existing Costing records, then click Yes.
Open the downloaded Excel file.
In the column C Hide field, enter Yes next to each costing code you want to hide.
Do this for all costing codes you want to hide, then save the Excel file.
Go to Settings, click Costing Import, and import the updated Excel file. Click Yes to confirm.
You will see the message: 'Costing Import Successful'.