I Can't Unload Filament
On the LCD panel, select Utilities > Change Filament > Unload. Wait for the extruder to heat to the set temperature.
If your extruder has a lever arm at the side, push it down and hold it in place. If you have an extruder without an arm at the side, continue to the next step.
Push a short length of filament through the heated extruder. Then try pulling the filament out again. Repeat as necessary.