In order to delete a language from your profile in your browser window, click Change Language in the upper left hand corner.
All the languages that you have studied will slide out from the left side of the screen. Click the X next to the language you want to remove. Note: if you want to add the same language in the future, your previous progress will have been saved.
In order to delete a language from your profile in the mobile app, tap the icon that represents the language you are learning in the upper left hand corner of the screen. This will show you all the languages you are learning. Tap Remove Language underneath the language you want to remove.