Setting Out of office using OWA

Setting OOF from OWA is simple enough

Login to your mailbox (if you are o365 you can use outlook.office.com to login to your mailbox).
Once you are in your mailbox click on Settings the Gear icon right hand side top of window.
And click Automatic Replies.

This will take you to the Automatic Reply page.
From here you can enable or disable your Out of office replies.