Keep in mind. If you go into SIMPLE for your recovery model, you with stand to loss all data to the point of your last full database backup (if your backups are in good condition). If you are in FULL recovery you with stand to lose data to you last log backup and a max of time up till your last full database backup. You would need to restore the full and play back the logs to the point you need.
Like @jgehling said. Either shrink the log now, by switching into SIMPLE first then shrinking the log manually. Then put it back to full and set a plan to start log backups at a certain interval. You will need to do a full database backup first to establish the backup chain for the logs.
After you correct this you need to have that hard discussion with management on the SLA’s you need to establish regarding your Epicor data. And what your company is willing to allow for potential data loss in a restore event.
A great resource to understand how SQL backups work is this ebook: Free eBook - SQL Server Backup And Restore
There is also another for transaction log management: SQL Server Transaction Log Management by Tony Davis and Gail Shaw - Simple Talk