Hello mate
In EPO 3.6.1, once you have logged in, on the left hand side list of groups and site that you have created, you will see your server name close to the top (above "Directory")
Click on your server name and on the right hand side you will see tabs for "General" , "Scheduled Tasks" etc
Click on "Scheduled Tasks" and here you will see a list of Server Tasks, where you will find the Replication Tasks listed. There can also be other tasks listed here such as server update tasks, which update your EPO with the latest DATs etc, so be sure on which tasks you are selecting.
Click on the task and either delete them or disable them by going through the tasks wizard.
Hope this helps
McAfeeGeek