Press the Options button in the top right corner and from the sections on the left select Out of Office Assistant. If you have access to your mailbox via OWA (ask your mail administrator if you do not know), then you can also try to turn it off there Under certain conditions this could fail and you’ll have to use another method in order to turn it off or reset the OOF. The normal way to turn on/off your Automatic Replies (aka: Out of Office Assistant or OOF) in Outlook is Is there any other way to disable it again?
Before my holidays I turned on Automatic Replies but now I cannot turn it off anymore.