YES, it is VERY IMPORTANT to remove any current antivirus programs from your operating system prior to installing or activating your ESET Antivirus program.

Serious conflicts can occur on your device by having two active antivirus programs. This can negatively impact your system resources (i.e. cause your pc to run slower) and the conflicts may also cause system issues and crashes when attempting to view or utilize the same file.

Please Note: 

Very often the typical removal via the Windows Add/Remove programs functionality, is not sufficient, when uninstalling previous antivirus.

We therefore recommend that you remove your previous Antivirus program using the ESET Antivirus Removal Tool. You may use the tools available here.