Figured this out in IFS as below.

Revoke authorization. This bring the header into ‘released’ state

RMB on the header and ‘Changed to Planned’

Start removing the lines via delete

Hi @Asela Munasinghe ,

As I know there is no way to cancel a purchase requisition. You can close it or delete it. Additionally, you don't need to revoke authorization. You can delete lines directly. After that, you can change as "planned". Finally, you could remove the PR.

@hhy38 I don’t think you can close it without converting to PO. 

For me, deleting lines directly without revoking authorization isn’t also possible since I get the error message “Remove Not Allowed in State Partially Allowed” 

Maybe you’re referring to a higher version. But mine is App9

@Asela Munasinghe Yes, it is true. We must convert to order or quotation to close the requisition. I am deleting it with IFSAPP, maybe it could have the privilege. Or your version could have an event to prevent it. So, there is no other way like. 

Oh no, this only for the regular user who would occasionally remove such a Purchase Requisition, so I wouldn’t rely on IFSAPP here.  Thanks for your responses. Maybe I didn’t explain it better - converting the PR to PO is not an option! The user no longer requires the PR. Your suggestion to convert it into PO might cause extra concerns for the business. 

I would still go with the solution I suggested in the first comment. Thanks. 

Agree with you. I think there is no other way.