You can leave an alliance through the following:
-Click on the Alliance icon at the bottom right of the main screen,
-Click on Alliance Management
-Click on Leave alliance
Note: When you leave the alliance, your contributions and your medals (including the ones in your backpack) will disappear. You will get a warning message before leaving the alliance. Are you sure you want to leave the alliance? You will lose Medals and alliance honor when you leave the alliance.
In case the alliance captain wants to leave the alliance, he can move the leadership to any member of the alliance and then leave. Or he can disband the alliance by doing the following:
-Click on the Alliance icon at the bottom right of the main screen,
-Click on Alliance Management
-Click on Disband Alliance.
-Enter the alliance name and click confirm.
Only the alliance captain can disband the alliance.