I've been hesitant to reply due to the fact that dealing with removal and reinstall of .Net can be a pain at best of times. Doing so is a risk and might leave you worse off than you are now.
The last set of MS updates included .Net security patches, one of which damaged my system so I couldn't apply all the updates even after downloading manually. I was able to fix it over a few days of reading and downloading tools but it was hit-and-miss and I was without any .Net for a while until Windows Update started working again. It was as much luck as what I did that got it to properly install again.
Some games and other applications will use .Net as well as a lot of developer tools and languages.
If your going to uninstall .Net you'll need the proper tool and guide found here; https://blogs.msdn.com/b/astebner/archive/2008/08/28/8904493.aspx?Redirected=true
.NET Framework Cleanup Tool User's Guide
You might want to go to the MS download page and/or search for the .Net framework your replacing and download them first. IE: "dotNetFx40_Full_x86_x64.exe" or "dotNetFx40_Client_setup.exe" and/or "dotnetfx35setup.exe".
.NET Framework Setup Verification Tool User's Guide is another tool and guide you can use to check things; https://blogs.msdn.com/b/astebner/archive/2008/10/13/8999004.aspx?Redirected=true
Microsoft .NET Framework Repair Tool - This can be found here; https://www.microsoft.com/en-us/download/details.aspx?id=30135&WT.mc_id=rss_alldownloads_all
Good luck with whatever you choose.