Color sampling points can be added to, moved around in and removed from your Photoshop images using either the Eyedropper tool or the Color Sampler tool. The process is similar with both, but varies slightly depending on the tool you are using.
To enable the Color Sampler tool, click and hold the Eyedropper button in the Tools bar and then select Color Sampler Tool from the flight menu.
Moving a Sample Point
If you are using the Eyedropper tool, hold Shift and mouse over the sample point you want to move. If you're using the Color Sampler tool, simply mouse over the sample point. The cursor turns into an arrowhead with a Crosshair symbol by it; click and drag to move the sample point.
Dragging a sample point outside the boundaries of the image deletes it. This is also the case if the sample point ends up outside the image through some other action, such as cropping.
Deleting a Sample Point
If you are using the Eyedropper tool or if you have an adjustment dialog box open, hold both Shift and Alt and mouse over the sample point you want to delete. If you're using the Color Sampler tool, hold Alt while you mouse over the sample point. The cursor turns into an arrowhead with a Scissors symbol by it; click the sample point to delete it.
Deleting All Sample Points
When the Color Sampler tool is active, the Options bar includes a Clear All button. Click this button to remove all sample points.
Moving or removing sample points can't be undone — you'll need to move them back or add them again manually.