Mistakenly Change My Site Url From "General" In The Dashboard and Cant Login Again,wp-admi

I Mistakenly Change My Site Url frm omd.com to Omd.com/join From “General” In The wp Dashboard and ever since then i Cant Login Again to my Dashboard,as my Wp admin page reloads from omd.com/wp-admin to omd.com/join/wp-admin which brings a Page not found