If the action on a guitar is very high, you will find it tough to play the guitar. This means that the measurement from the strings to the straitboard is more. It is a three-step process in the lowering action on the acoustic guitar. The three steps are straightening the neck, lowering the nut along with putting up the saddle.
1) Straightening the neck:
Examining whether the adjustment of the truss rod may be required for lowering the action, first should clearly notice the neck of the guitar whether the neck of the guitar is bowed towards up or down.
If the neck of the guitar is bowed towards up, it will be slightly bent up whereas the guitar which is bowed downwards will have a bend towards down.
Inside the neck of the guitar, you will be able to find a thin and a steel rod which is called a truss rod. Depending on the design of the guitar, you will be able to see when the nut is getting adjusted from the peghead or else near the soundhole.
If the truss rod will only be found near the soundhole, all you want to do is that you have loosened the strings present before you start adjusting the truss rod is nothing but the belt.
The accessing of a tool in the soundhole much easier because of this. But ensure that none of the strings are removed completely. With the help of a nut driver slowly turn the head of the screw or nut present in the truss rod.
There might be a necessity where you should smoothen a truss rod nut in the case where you own an old guitar or also in the case where the truss rod has not been turned ever.