Hello Tia ~

Log files are a function of SQL Server, not DNN... so they are managed outside of DNN and cannot be manipulated with a scheduled task ( at least none that I am aware of to date ).  Being so large, it sounds like your database is set for full logging, which is usually only required for websites where mission critical information must be able to be restored up to the moment of failure ( if a disaster were to occur ).  Most personal, or non ecommerce sites are just fine with simple logging.  I'd inquire with your host about their backup & restore options... or about whether they can schedule a job for you to shrink your database on a regular basis.

Cheers

Scott Willhite, Co-Founder DNN