Here are the steps on how to lower the tuning of your guitar by one whole step:
1. Detune the sixth string. Turn the tuning peg for the sixth string (the thickest string) counterclockwise until the string is loose enough to slip out of the tuning peg hole.
2. Reinsert the sixth string. Once the string is loose, pull it out of the tuning peg hole and insert it back into the hole, but this time one fret lower. This means that the string will be resting on the seventh fret instead of the sixth fret.
3. Tighten the sixth string. Turn the tuning peg clockwise until the string is tight enough to hold its tuning and produce a clear sound when plucked.
4. Repeat steps 1-3 for the fifth, fourth, third, second, and first strings.
5. Check the tuning of your guitar. Once you have lowered the tuning of all of the strings, use a tuner to make sure that they are all in tune with each other.
When you are finished tuning your guitar, you will notice that the strings are looser and produce a lower pitch than they did before. This is because you have lowered the tension on the strings by moving them down one fret.