Cannot change control of balance sheet (primary cost elements exist)

What causes this issue?

You want to change the balance sheet configuration settings for this
G/L account although it has already been created as a primary cost
element in the appropriate controlling area.

System Response

You system will not allow you to change the balance sheet configuration
settings.

How to fix this error?

Check whether the account was created correctly as a primary cost
element in Controlling. If this is not the case, you must delete the
incorrect cost element, which will then allow you to change the G/L
account master record.

Error message extract from SAP system. Copyright SAP SE.