You may want to lower the armhole of your shirt/bodice/top for a more comfortable, or looser, fit.
To do this, take your front and back patterns.
Decide how much you would like to lower the armhole by.
Mark this distance on the side seam, measuring down from armhole.
Mark this point on both front and back patterns (this is your new underarm point).
Redraw the armhole, by drawing a smooth curve between the new underarm point and the outer shoulder edge. The curve will gradually ease back into the original armhole line.
Redraw front and back armholes.
Cut along the new armhole line to remove excess from both front and back armholes (or trace off separate pattern, with lower armhole).
And that's it!
As this pattern is sleeveless, no sleeve adjustments are needed.
If there was a sleeve, you would need to walk the sleeve pattern into the armhole, to find out how much longer the armhole now is. You would then adjust the sleeve accordingly, by distributing the extra length throughout the sleeve cap. If it is only a small amount (as would be the case in this particular example) you could just distribute the extra length either side of the bicep line and redraw the cap. If the armhole has increased by a larger amount, you could cut and spread the sleeve cap to evenly distribute the extra length in the sleeve cap (between the notch and the side seam).