you understand? so why cut away instead of cutting it closer and making the job easier?  i wouldn't want you to risk accidentally cutting the part itself and end up damaging it. its quite easy to spot since  weakened plastic leaves a small white mark on the area where the sprue was cut.

so now thats done, you are going to remove the nub with your hobby knife or cutter. carefully slide the cutter in a forward sideward movement. while your pushing the blade, slowly slide it sideward at the same time, because if you just simply push the blade, you risk stressing the plastic, leaving a white mark at the end of the nub which would look bad especially if your doing a paint less build .

be careful not to cut yourself while doing this.

start doing this process from the top of the nub, and slowly work your way down. repeat this until the blade glides smoothly across the surface of the plastic. but the work here isn't done, though not clearly visible, there are still small, rough plastic leftover.

to remove this, rip a small piece of fine sand paper, i suggest starting with 600 grit.

  

sand lightly, and finish with 1500 grit or higher. (the higher the number the smoother the surface.)

the nubs should not be seen and the surface should be smooth to the touch. don't think its too easy, imagine if you do it to a hundred more parts, its really tiring and needs a lot of patience, but it does give fantastic results.

i don't usually do this step by step, but for those who don't paint their kits, this makes a big difference.