Como mencionado em este comentário
sudo apt purge libapache2-mod-php7.0
funcionou para mim também.
Tentando fazer uma instalação da lâmpada, recebo este erro:
$ sudo apt-get install libapache2-mod-php7.0
Reading package lists... Done
Building dependency tree
Reading state information... Done
libapache2-mod-php7.0 is already the newest version (7.0.15-0ubuntu0.16.04.4).
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
1 not fully installed or removed.
After this operation, 0 B of additional disk space will be used.
Do you want to continue? [Y/n] y
Setting up libapache2-mod-php7.0 (7.0.15-0ubuntu0.16.04.4) ...
dpkg: error processing package libapache2-mod-php7.0 (--configure):
subprocess installed post-installation script returned error exit status 1
Errors were encountered while processing:
libapache2-mod-php7.0
E: Sub-process /usr/bin/dpkg returned an error code (1)