If the MATLAB uninstaller was unable to complete, try executing the uninstall.exe from $MATLAB\uninstall (where $MATLAB is the folder where MATLAB is installed). For example:
If you are unable to complete the uninstaller, you can try the following workarounds:
1) Re-install MATLAB and overwrite the current MATLAB folder. This will re-create uninstall.exe and should allow you to uninstall once complete
2) Manually delete the MATLAB installation folder.
Aside from removing the installation of MATLAB, you can remove the MATLAB entries from the Windows System Path. For help modifying the Path in Windows, see the related article:
"How do I set my system path under Windows"