To switch between PHP5 and PHP7 in Apache, it is necessary for PHPBrew to enable & dissable custom apache modules. These need to be removed as well. Depending on the existing permissions it is not possible to just reinstall the apache module. Thats why they are still loaeded & running, even if the PHPBrew folder and PHP itself is already removed.
The following commands removed all PHPBrew files and reinstalled regular PHP on my system.
### remove phpbrew
rm -rf ~/.phpbrew/
rm -rf /usr/local/bin/phpbrew
vim ~/.bashrc #remove phpbrew settings
### either edit modules, or remove completely
sudo rm -rf /etc/apache2/mods-enabled/php*
sudo rm -rf /etc/apache2/mods-available/php*
sudo rm -rf /usr/lib/apache2/modules/libphp*
### reinstall php
#dpkg -l | grep php
#sudo apt-get remove --purge php*
sudo apt-get install --reinstall php php-common libapache2-mod-php