You will unlock that world soon enough, young Wizard. The only way to remove a quest from your Quest Journal is to actually complete it.
Once you have completed all your required assignments in Wizard City, Merle Ambrose will ask you to investigate Krokotopia.
Once you have been given that quest, you can access the Spiral door by entering Bartleby the World Tree.
After you’ve completed Krokotopia, you can move on to Marleybone, then MooShu, then Dragonspyre. You can visit Grizzleheim at level 5, but cannot return until level 20.
