How do you remove a seat from a Yahama Dirt Bike?

Answer 1

Always give year, make, engine size and model # when asking questions. We need all of that info to give an informed answer.
Every bike is different.
Look up your bike here, go to Seat and figure it out.
http://www.bikebandit.com/partsbandit/OEM-parts-nav.asp

Answer 2

Depending on what type it will be under the fender, right beneath the rear of the seat. On the larger bikes there are 2 bolts that screw in at the rear of the seat that also hold on the rear number plate. They should be 10mm bolts. once these are off then you just slide the seat back and voila your seat is off. Hope this helped.