Tamiflu, for example, blocks neurominedase (the letter N in the abbreviation for influenza) and prevents it from multiplying. And immunity fights the virus. Since 2011 (then I started taking Tamiflu at the first sign of the flu) I have never had a strong flu. The temperature did not rise above subfebrile, full recovery (according to sensations) occurred in a day or two.
It is impossible to directly destroy a virus in the body: it lives and reproduces itself, integrating into the structure of cells, therefore, the destruction of viruses means the destruction of infected cells. Such a "action" can cause serious harm to the host organism.
However, it is possible to block the multiplication of the virus and the re-infection of healthy cells. Most antiviral drugs work in this way.