To deactivate your Plays account, just log into your account on the web, then go to the Edit Profile menu. From there, you'll be shown the Basic Info page and there is an option to deactivate linked at the bottom of the displayed area.

When you select "Deactivate Account", you are then prompted to enter your password and confirm the action, at which point your deactivation should be complete.

Please keep in mind that once you deactivate your Plays. Account, you will no longer have access to it. If any Social or Game Accounts are still bound, they will remain bound. We highly recommend that you unbind all game and social accounts before deactivating the account in case you want to bind them to another Plays account.