The easy way to change Winrar into English language is not uninstall and install again. What you need to do is just remove 2 files that's all.
Go to C:\Program Files\WinRAR folder remove RarLng.dll and Winrar.lng.
If winrar change English to other language maybe is cause by windows region and language setting. Go to control panel find Region and Language -> Administrative tab -> Change system locale to English.