You can resign from a specific tournament by accessing the Tournaments page in your account's settings. Please only resign from a tournament if you no longer wish to participate in that tournament, as your participation records will be permanently deleted.
Try either of the following:
1) Click on Your Account > Tournament in the left hand navigation
2) On the Dashboard, click on Settings > Tournaments
3) Click on Tournaments (on the left) to open the tournament navigation window. Click on the "Resign from a tournament" link at the bottom of the list.
1) Tap on the Player icon (top right). Now tap on Settings > Tournaments.
2) Tap on the navigation icon in the top left hand corner. Tap Tournaments (abbreviated to Tourns on some devices) > "Resign from a tournament" link at the bottom of the list.