Howto remove a contact from phone

I switched the phone, it seems there were contacts stored on it.
i have linked my nextcloud account
now i have two contacts for some names.
i can see that when i select edit.
i can edit the phone contact, but i can not delete it
and it seems that the phone contact wins: shows the avatar, details etc. rather then the one from nextcloud account
any ideas how to delete the contact in contact app or cmd line ?

Thanks ! / experia x

Maybe my bug report about beeing unable to disable CalDav is related. There seems to be a general issue to contact syncronization and contact merging while using different accounts.
CardDAV account disabled, but still shown as contacts