If you want to update the .NET Framework on your System, check the set of steps given below:
Launch the start button, and go to the Control Panel.
Thereafter look for the Programs and Features tab, and click on Program.
Now look for .NET Framework under the Name tab.
Choose the Change/Remove option to uninstall the older version of the .NET Framework.
Now, follow the on-screen instructions to complete the uninstallation procedure.
Again, click on Start, and search for Windows Update Now to see the new .NET Framework in the Update or Installation option.
Lastly, follow the information present on your screen to complete the process.