The solder resist layer can be edited to remove an area by adding a shape (resist exclusion). The resist can be removed but the default openings for pads cannot currently be removed, however this does meet the requirements for example when you wish to remove the resist over areas of copper used as a heat sink, or tracks that may get hotter than normal for example.
Adding a regular shape is simple, but to exclude the resist over a specific track route can appear to be complicated. The following provides an example of how to simplify this.
With an example track as shown.
Select using the mouse or CTRL+LMB on individual segments to add or remove selected segment such that required track route to be excluded from the solder resist layer is highlighted.
Use CTR+C to copy and CTRL+V to paste a copy.
With copy selected right click and select "Change Shape Type..."
Now change the shape type from "Track" to "Shape", this is required to allow it to be moved to the solder resist layer.
You may select properties to change the style, i.e. the width of the excluded resist and move the shape to the solder mask layer.
The shape is now correctly defined. Select and drag to the required location as shown.
Here you see the bottom copper track with the bottom solder mask cut out.
Note the solder mask shape colour was changed to brown to allow it to be visualised for this FAQ.
How to add a solder mask layer if it is not already visible.
Use the Interaction Bar (short cut F9) and select Layers tab to see what is available for editing in your configuration.