Hi'
Thank you very much for quick reaction! 
The project cannot be deleted - even if nothing is changed at the project after automatic creation
I have tried to put deletion flag and deletion indicator at the project. That does not help.
Im not familiar with the actual archiving run and do not know if it is possible in our system (we have never archived anything).
I just wondered if we are the only company in the whole SAP-world who had made such a mistake at an existing contract and now are stucked in a deadlock 
But thank you for your response anyway! 
Best regards
Lone