Is it very risky to install TCs?

[Your Computer]

Can you tell me how to in- and uninstall TCs without Desura, Your Computer?

If they come with install instructions, it would normally be found in some sort of "readme" file or any other obvious name. They normally don't provide uninstall instructions since they tend to just tell you to extract "here" and hope it works. In those cases the uninstall process is very tedious, as you'll tend to have to examine the entire archive folder structure and see where everything is located, then find them in the folders where they were extracted to, then delete them. Desura tries to do all this work for you, and thankfully does a pretty good job at it.