Hi, we can certainly delete the Marketing channel processing rules. However there is a open bug for the same and under progress.
Please open a ticket with ClientCare supplying details (Company, Report suite) and then the incident can be linked to the open bug.
Workaround:
1. Like you mentioned, move the rule at the bottom in the list.
2. Create a condition based on the variable which you have not implemented yet. Like evar250 for an instance.
Regards,
Jaspreet