If you see a message saying
"Another account is active on your device. Contact WR support if this message continues to appear: email@example.com",
clearing registry is what may help you. Here are steps on how to clear your registry:
— Press Win+R keys;
— Type 'regedit' into the text field of the "Run" dialog box and click 'OK';
— Go to HKEY_CURRENT_USER→ Software → Pixonic → War Robots;
— Select all entries in the opened directory (War Robots) and delete them;
— Restart your PC.