The phrase "to forget the world" means to ignore or put aside all the problems and worries of the outside world, and focus on oneself or something enjoyable instead. Full definition
And don't forget the world of games and apps instantly available at your fingertips. (finder.com)
Let us not forget the world has also a mission and the Christian church has to find the place of her mission in the mission of the world. (religion-online.org)
Forget the world around you for a while and feel the joy of living... Your deserve it. (theroyalcaribbean.com)