Hi Jeff,

On a phone, you can logout by clicking on the menu icon top right, then scroll to My Account, then scroll down a bit further and there is log out button.

But mobile websites don't work like apps. It's not running 24/7 on your mobile phone. You can just close the web browser.
There is really no need to logout unless someone else is using your phone and you don't want them to use your fishingreminder account.

Cheers
Mark