Go to this directory.

etc/apache2/apache2.conf

you will find below code with AllowOverride none.

<Directory />
    Options FollowSymLinks
    AllowOverride none
    Require all denied
</Directory>

<Directory /usr/share>
    AllowOverride none
    Require all granted
</Directory>

<Directory /var/www/>
    Options Indexes FollowSymLinks
    AllowOverride none
    Require all granted
</Directory>

Edit the code and make AllowOverride none to AllowOverride All.

<Directory />
    Options FollowSymLinks
    AllowOverride All
    Require all denied
</Directory>

<Directory /usr/share>
    AllowOverride All
    Require all granted
</Directory>

<Directory /var/www/>
    Options Indexes FollowSymLinks
    AllowOverride All
    Require all granted
</Directory>

Start the Server again and eco out the phpinfo();

You will see mode_rewrite enabled.