Heatbed control with Pronterface
3D printer get the temperature settings from g-code file. The firmware settings for min and max temperature are just safeguards.

You should verify instructions within the g-code file. If you are not familiar with g-code, take a look to wikipedia. List of g-code instructions for marlin firmware is here.

Instruction responsible for setting bed temperature are M190 and M140. Open your g-code file and search for lines containing them. If you delete these lines then the bed temperature will be not set during print. Additionally it means that it is set by your slicer. 

In Slic3r you should check Printer settings &rarr; Custom G-code &rarr; Start G-code if it contains one of mentioned instructions and possibly remove it.