Open system management > data maintenance.

Select the historical data you want to clean up, such as historical phone bills, and then select "Historical phone bill cleaning", select the start time and end time of filtering, and then click "Filter".

Note: If the start time and end time are not checked, it means filtering all historical calls.

Select the date on which you want to settle the bill, then click Delete, and finally apply the date.

Note: Data in system log cleaning is not allowed to be deleted.