Upon reviewing your concern, I understand that you want to know to change the settings of your Maximum Security to automatically delete your security report logs in shorter time frame. Let me help you with this.
I do apologize however, there are no option to delete it manually or to adjust the automatic deletion of security logs since it is used for tracking purposes so that the users will know what kinds of threats have been detected and removed by Trend Micro. Also, there are times wherein there might be some False Positive detection from some of the programs or applications on your computer wherein it can be detected as a threat and Trend Micro can remove a certain file inside it making the program unusable. If you still have the logs, you may just view it inside your Trend Micro program and restore it.