You can't uninstall it because it a part of Windows OS but you should be able to disable it. It could be that Windows stops you disabling it in order to protect you and that only installing other AV/firewall software is allowed to disable it. Just guessing really but that's how it seems to me.
What is Markdown?
Markdown lets you add more formatting to your post. Simply type in your post and it will display as written.
If you wish to add bold or italic characters, add a hyperlink to another website, a heading or a horizontal line, simply use the relevent icons above the text input field.
A preview of your post will appear in the grey box below. If you make a change and you're not happy, simply press the back arrow icon to undo.