Try launching that software you accidently downloaded and see if it has an Un-Installer. If so, run it and hope that helps.
If it doesn't have an un-installer, then find it in the application folder and drag it to the trash.
For future reference, most printers/all in ones can run fine without having to install the manufacturers software, which in my opinion causes more problems.
For my All in One Brother printer, I use...
Printing is totally handled by Mac OS. Just download the driver you need.
Scanning, I use Image Capture which is located in your Applications folder.
Of course, faxing is a totally different issue. I don't have a land line, so I just scan and email.
Good luck.
Adam