Hello,
If I understand well, my advice would be: You do not have to uninstall the old printer, the only thing you need to do is install the new one. I believe you have a CD with drivers with new printer, so just instert the CD in the CD ROM, it will opens up automaticaly. In case you do not have the CD, you can download the drivers for your new printer
here. You just need to select the operating system you use, click Next, and then choose Driver - Product Installation Software. After the file is downloaded, you just double click on it, and follow the instructions.
Hope this helps, in case you have any further questions, please just add a comment
Lucas