Hi Emanuel,
I don't think so you can delete the requirement assignment tab in standard way of SAP MRS and moreover it's not advisable. May I ask you where you see this planning information? If you want to remove the service order why don't you use the status control functionality. Where you can avoid the service orders based on the technically completed. If you need help in this please get back or if you manage to find out some other solution please share.
Thank you