INVALID TOOL: I recieved a command for Tool #2, but I only have one tool

Ok so when i try to use the left side of the extruder it says "INVALID TOOL: I recieved a command for Tool #2, but I only have one tool"But i only want to use the left extruder and not use the dual extrusion. How do i fix this?

THIS IS FOR MAKERBOT 2X

left extruder is designated tool 1,
Right extruder and bed are tool 0
You need to alter it in the initialising gcode.

What slicer are you using ?