If you turn the tension knob all the way clockwise this loosens the tension on it. In that position you can pull the idler arm away from the hobb gear and pull the filament up.
After you’re done cleaning it with the pull and re-feed fresh filament, don’t forget to re-tension the idler arm. The tension knob drives a hex nut which presses a spring. Turning anti-clockwise pushes the hex nut into the spring and adds tension. Turning clockwise pulls the hex-nut away and loosens tension. You can see the metal side of the hex nut through a slot on top of the tension adjuster. For normal operation that nut should be roughly 1/3rd to perhaps as much as 1/2 of the travel. I tend to operate my printer at the 1/3rd position.