Hi Julia,
Though deleting the country templates is not recommended I had never succeeded to get why :-).
Company code 0001 is a bit differrent case - it contains some (even legal) presets for Germany (incl. e.g. tax codes) and should be kept.
However, you have several options to prevent postings in a company code:
- delete the fiscal year variant in OBY6
- block a chart of accounts in OB13
- create a validation rule in OB28
hope this helps
John