contact-api is used to add/delete a contact with comandline for Android.
Install the app and grant WRITE_CONTACTS READ_CONTACTS and Autostart permission.
Add a contact:
am broadcast -n com.oufme.contact_api/.ContactReceiver -e operation add -e name "Kitty" -e number "1234567890"
Delete a contact:
am broadcast -n com.oufme.contact_api/.ContactReceiver -e operation remove -e name "Kitty"