This guide will help you easily link your origin account to your steam one, so you can finally delete origin.
Launch the game
Once you launch a game, you’ll find the following screen.
Click on register.
Enter your account details (the one to link)
Once you click on Register, you’ll be prompted to enter your account details.
NOTE: MAKE SURE YOU ENTER THE CORRECT ACCOUNT TO BE LINKED OR ELSE THE PROCESS OF UNLINKING WILL BE NUTS.