In BMU version V200R003, in this case, you can schedule a timeframe for the deletion of the operation and CDR logs as per below:
From log level you are able to choose the type of the logs that you want to schedule for deletion and then you can Enable the "Delete operation logs" tab.
Then you have to select the specific time to delete the logs for a certain period of time by typing in "Operation log storage Duration (Months)" tab.
For example the deletion of operation logs I set it to every 1 month.
The same procedure you can apply for CDRs logs also.