You may uninstall using either of the following methods.
SU Device-
Go to the Software Center in your list of applications. Search for Mathematica then select Uninstall.
Personal Device-
Programs in Windows can be uninstalled in Apps & features. In the search bar, type in "Apps & Features" and hit enter.
From the Apps & Features window choose your version of Mathematica. Then Click uninstall.
You may be asked for your windows administrator credentials to complete the uninstall process.
For older version of Windows, open the Control Panel. Click the Start menu, type "Control Panel" and hit enter. From there, under Programs, choose "Uninstall a Program".
In the next Window, scroll down to your version of Wolfram Mathematica. Click on the program and choose Uninstall.
You may be asked for your windows administrator credentials to complete the uninstall process.
If desired, you can remove the following directories.
These folders may be hidden on your computer. You may need to enable your account to see hidden folders.
Note that the documentation needs to be uninstalled separately.
SU or Personal Device-
Before uninstalling, back up any Mathematica projects
Open the Applications folder.
Drag Wolfram Mathematica to the Trash icon in your Dock bar.
You may be required to enter your Mac's administrator credentials to complete the process.
Any remaining files in the following locations may be deleted.
These folders may be hidden on your computer. To navigate to a hidden folder, open the Finder application. Press Command + Shift + G to open a file search dialog and enter, for example, “~/Library/Mathematica/”. Finder opens the hidden folder.
After all desired files have been deleted, empty your Trash Bin and restart your Mac to complete the removal of the software.
Note that the documentation needs to be uninstalled separately.