ERR_EMPTY_RESPONSE after adding new language

Hello Polylang Community.

I installed Polylang in a brand new instance of WP 4.7.3, and as soon as I added a 2nd language (French/CA), the site stopped responding.

I’ve tried disabling the plugin by changing the name of its directory and the site begins working again.

I’ve also tried different themes, but the error persists.

Has anybody had this experience and have a fix to recommend?

If not, what’s the cleanest way to uninstall the plugin without having access to the admin back-end?

Thanks,
Adam