What is it
It’s most likely a part of the WPML. This is based on a quick copy paste of
wp_installer_network into the github search box.
There’s also a small chance this is the Types plugin, but you mentioned you had a multilingual plugin installed.
No references to
wp_installer_network are found in WordPress itself.
and how delete it ?
You would need to ask this in a WPML community but the easiest way is to deactivate WPML. If you want to keep WPML but still resolve the problem you will need to ask this in a WPML community as 3rd party plugin questions are offtopic here