I have never experimented with asking AE to automatically delete large report files so I don't know if such an option exists. And the report you discard could contain critical business information.
Our approach was to address each over sized report one-at-a-time and fix them at the source. 95% of the time the information that inflates the report size is of no use to anyone, and the process of generating those reports wastes machine cycles. So if you fix them at the source, your systems will run faster! (We particularly saw large performance improvements when we fixed some large Oracle dbms_output reports, because it is expensive for Oracle to write out to flat files.)
We were so pleased with making our systems run faster, that once we fixed the over sized reports, I then ran the following database query to identify the largest reports that were inside of the database, and we optimized many of them too;
select oh_name as job_name
--, ah_timestamp1 as activation_time
, dateadd(hour, datediff(hour, getutcdate(), getdate()), ah_TimeStamp2) as Start_time
--, ah_runtime as runtime
, CONVERT(varchar, DATEADD(ms, ah_runtime * 1000, 0), 114) as runtime
, count(*) as report_size
from uc4.dbo.rt
, uc4.dbo.ah
, uc4.dbo.oh
where ah_timestamp1 > cast('20171210 00:00:00:000' as DATETIME) -- how far back in time
and ah_oh_idnr = oh_idnr
and rt_ah_idnr = ah_idnr
and not oh_name in ('APPUTILP', 'AE_PROD#WP001') -- Objects to exclude from the selection
group by oh_name, ah_timestamp1, ah_timestamp2, ah_runtime
having count(*) > 500 -- MAX_REPORT_SIZE is set in UC_HOSTCHAR_DEFAULT
order by 2;