Originally Posted by veganbikes

Generally adjusting the seatpost is done with a simple hex wrench. In some cases it is a quick release and on some cheap and some older bikes you might need a box wrench of the proper size. It all depends on what you have. Since you don't have photos posted nobody but you will be 100% sure but more than likely it is a simple hex wrench. If it is a vintage bike I would recommend pulling out the seatpost and re-greasing it and if it is a modern bike I might do the same because I wouldn't trust BD who bought their name to do so. A seized seatpost sucks!