Perform the following steps to disable a Steam Controller:

1. In Steam, click on the Big Picture Mode button at the upper right corner
   This will open Steam in Big Picture Mode, in full screen
2. Click on the Library button
3. Select Rocket League
4. Click on the Manage Game button in the left-hand column
5. Click on the Controller Options button
6. Click the Steam Input Per-Game drop down box

7. Select Forced Off
8. Launch Rocket League to confirm that your controller is recognized

Note: If your input is still not being recognized, you may need to relaunch Rocket League