So we'll assume you are not rooted and that you've not taken any other measures to clear them.
Do you know where they are installed, i.e. as user or system apps? Are they set as device administrators - if so the AV won't be able to uninstall them until you change that (Settings > Security > Device Administrators).
If they are installed as system apps then the AV will also not be able to uninstall them unless you are rooted. That said, if you are not rooted and they are installed as system apps it's more likely they came with the phone, and maybe the AV has reported a false positive (that does happen). Try a second opinion, e.g. a scan with MalwareBytes, in this case.