Remove demo upload subpage to Website

I have a website –
https://www.bowvalleygourmet.ca/

We paid a “professional” to upload a new theme. Instead of just uploading it to our existing site, he created an entirely new webpage, with a fresh install of the theme at https://www.bowvalleygourmet.ca/new

This new install has it’s own unique login (separate from my original, functional website) at https://www.bowvalleygourmet.ca/new/wp-admin.

We quickly discovered it was much easier just to upload the new theme to our existing site, which we have done. Now that fresh install of the theme is eating up space on our server. How would I delete everything they did? Thank you!