Exercise extreme caution when removing data.

One must be very careful when deleting data. It’s far too easy to delete the wrong data by mistake. This kind of error can lead to extensive system downtimes and upset clients.
Before removing any data, query the data set to be deleted and examine it closely. Sometimes this simple action can reveal data elements that you should not remove. For more massive data sets, sample the data multiple times. Also, one can summarize the data to be deleted and look at counts and totals.
Also, make sure you have backups. It can be extremely unfortunate to delete the wrong data accidentally and then learn, too late, that your backups are not functioning correctly.
Even highly experienced people make mistakes. Don’t get cocky!