You can archive a contact in Dex to hide the contact from most views. Archived contacts will not be synced, or show up in contact search.
Why archive contacts instead of deleting them?
Archived contacts can be restored at a later date. If you've met someone that you may not want to keep for now, but may need later, this is a good option.
Archived contacts keep group/timeline relationships - if you'd like to hide a person but want to keep related groups and timeline items.
Archiving Contacts
On a contact, click the options, and click 'Archive'
On a contact table, select one or more contacts, click 'Archive