While Turmoil is active, switch from curses to regular prayers using the altar in the White Knights' Castle.
Requirements: 95 Prayer, unlocked Ancient Curses.
In order to complete this task you must have the ability to swap back to prayers at any altar enabled. If you don't get the option to switch back to normal prayers at the altar, visit the Zaros Altar at the Senntisten Temple. When praying at the altar there, you will get an option to enable prayer switching anywhere.
Souce: rswikia
L2Google.