How to complete remove all links to default PHP version?
Try this:

sudo mv /usr/bin/php /usr/bin/php5
sudo ln -s `which php` /usr/bin/php


The first command backs up the old PHP binary. It can still be used by invoking php5 in a command line. The second command symlinks the new PHP 7 binary to the location of the old PHP binary. Therefore, scripts that use the old location will start using the new PHP version.