Replace windows installation on Macbook pro with Ubuntu
First step would be to delete the Windows partition using a program like Disk Utility of GParted (which is often included in the Ubuntu live disk). This will give you some unallocated space that you may be able to expand the MacOS partition to. 

After you've increased the size to what you want, you can run the installation of Ubuntu and create a new partition out of the remaining unallocated space. This can usually be done during the installation process.