Recently I noticed, that there are some new user account on my win10. Unfortunately it wasn't me who creadted them.

(My win10 is using hungarian language, this image was taken in the start menu account submenu)

At first I deleted them, but they keep coming back. At one point I had about 6 of these. I suspected malwere or virus infection, because it happens in offline mode too, but my ESET Smart Security and Avast and Spybot search couldn't solve this issue.
Thank you in advance for your help.