Yes, you can.
There is a section in the manual that describes editing or creating your own navigation bars. See Chapter 5, "Creating Custom Navigation Bars".
If you're starting with an existing bar you should simply be able to remove the instructions on placing the Measure button and label.
In the ToolLabel section:
Remove all .Measure instances.
You can also remove this "area" tag later on in the template text file:
You can remove all the functioning elements of the Measure button from minimalist.jar without any adverse effects. Obviously, you will need to remove that part of the buttonbar graphic and build the rest of the bar normally to remove the button entirely.