Help with tdss killer

Hi
Ive been trying to get rid of some viruses and im pretty clueless about this so I need help. I didn't have any proper antivirus software and just had downloaded malwarebytes and advanced system care and I thought that would be enough anyway it wasn't which I now realise so a few days ago I downloaded avast which found a lot of viruses and a rootkit virus and I deleted a few of them but there were others that were in the windows folder and I wasnt sure if I should delete them and then my laptop deleted avast and I reinstalled it a few times but it kept doing it so just left it.

Just now I downloaded kaspersky tddss killer and it found 17 threats all high risk and again im not sure should i delete them or put them into quarantine. They are all called backdoor.multi.Zaccess.zen. Anyone know what I should do? Thanks.