I thought it was just a plugin of OBS ... Isn't it?
It's a plugin, but it seems it additionally replaces vital parts of OBS instead of just adding plugin functionality.
To get rid of it, and to avoid side effects, I would uninstall every program and trace of plugin, and remove any OBS-related configuration.
To uninstall app and plugins, use every OBS-related uninstaller found in Windows Settings->Apps.
Then use Windows explorer and manually remove any OBS-related directory in C:\Program Files and C:\Program Files (x86). It's C:\Program Files\obs-studio and/or C:\Program Files (x86)\obs-studio if installed to the default names. This will get rid of whatever is left by the uninstaller(s).
After that, go to %appdata% with Windows explorer and manually remove the %appdata%\obs-studio directory. It might be the se.live plugin leaves incompatible entries in the OBS configuration, so the only thing to get rid of that is to completely remove all OBS-related configuration.
After you removed all of the above, install a fresh downloaded original OBS. It should behave now as if there was never any previous OBS installed on that machine, so you can start over.