You can ruin any hair style you have created, using the Straighten channel, regardless of whether it was created using guides or Hair channels: The hair will be straightened, either by aligning it to the Normals, the guides or to the hair root segment.
From this menu you can select the method with which the hair should be straightened. Three available options are:
A straight element will be generated, based on the hair root segment, to whose orientation the hair will then adapt.
The hair will adapt to the orientation of the surface Normals at the hair root.
Use this option to straighten strong kinks in the hair, the kind that can be caused if you selected As Normal in the Roots menu of a Hair object’s Hair tab.
Use this slider to define the percentage of hair to be straightened.
Use this setting to define the strength with which the hair should be straightened. Use Variation to randomly vary the degree to which individual hairs will be straightened, within the settings of this channel.
Use this function graph to define the strength with which the hair should be straightened over the length of the hair.
A texture loaded here will use its grayscale values to define the strength with which the hair should be straightened across an entire surface.