ahtasnim are there other errors in the file? (the next error starts with the date and time just like this one)
The error you shared is probably the result of trying to run an SSH command, and not caused by trying to access the Flarum homepage.
If there's nothing else, you might also be able to see the error by going to https://<website url>/api or https://<website url>/api/discussions in your browser, which are the same API requests that Flarum does internally.
If you just want to recover access to the forum and disable the extension, you can either remove the extension with Composer, or go in the settings table in the database and remove the extension name from the enabled_extensions row (the value is a JSON array of strings containing the extension IDs)
